The UK Government is being urged to state if it will place key election rules on a statutory basis in the run-up to next year's independence referendum.

A Holyrood committee made the plea as it backed the general principles of the legislation that will enable the historic vote to be held.

The MSPs said they were confident that the Scottish Independence Referendum Bill "should provide a suitable framework for next year's referendum".

But they pointed out there was an "asymmetry" to the "purdah" arrangements - which are used to prevent governments from unveiling major new policies or announcing new funding deals in the period immediately before a vote.

MSPs on the Referendum (Scotland) Bill Committee heard concerns that, in relation to the referendum, these will not apply equally to the Scottish and UK Governments, with the Bill only regulating the Holyrood administration in this area.

Deputy First Minister Nicola Sturgeon has already stated there is "no reason to doubt the good faith of the UK Government's commitment to observe purdah restrictions equivalent to those imposed on the Scottish Government in the Bill".

The committee said: "Nevertheless, there is an asymmetry, and we invite the UK Government to indicate whether it would be prepared to put the purdah restrictions to which it is committed on a statutory footing."

While this was agreed by the majority of the committee, four MSPs - Labour's Patricia Ferguson and James Kelly, former Tory leader Annabel Goldie and former Liberal Democrat leader Tavish Scott - did not support this call.

The committee "strongly" supported having a four-week period of "purdah" in the run-up to the independence referendum on September 18 next year, with MSPs stating: "We would request that the Scottish and UK Governments each issue guidance to those public bodies for which it is responsible on the limits applicable to them during the 28-day period."

Their report also drew "to the attention of the parliamentary authorities" that, while the "purdah" period is due begin on Thursday August 21, Holyrood will not go into recess until two days later, thus creating an "overlap between the purdah period and a period of parliamentary business".

Convener Bruce Crawford said that, while the committee had "identified some issues that require clarification or amendment", "the whole committee was able to agree that the Bill provides an appropriate foundation for next year's referendum. Indeed, the Electoral Commission told us it was 'a strong piece of legislation' able to deliver a referendum 'that truly puts the voter first'.

"Although committee members clearly differ on what the outcome of the referendum should be, there was a high degree of consensus on how it should be conducted - and I am pleased that almost all the report's conclusions were unanimous."

The committee said the spending limits proposed by the elections watchdog, the Electoral Commission, for the referendum were "as good an overall outcome as is likely to be possible".

These set out that the two main campaign organisations, the pro-independence Yes Scotland and Better Together, which wants Scotland to remain in the UK, be allowed to spend up to £1.5 million. Meanwhile, the spending limits for the political parties would be linked to the share of the vote they achieved in the 2011 Holyrood elections.

MSPs on the committee said they were "generally satisfied with the rules on donations" although they did question if cash gifts of less than £7,500 should be reported to the Electoral Commission.

Organisations are required to report any donations they receive that are above this amount to the Commission, but the committee called on the Scottish Government "to consider further whether a lower threshold for reporting donations would be merited, and whether there should be greater public access to information about donations during the referendum campaign, in the interests of transparency".

The MSPs used their report to highlight the need to have enough polling stations for the referendum to cope with a high turnout.

"The committee, like many witnesses, is hopeful that turnout for the referendum will be high," it said.

"We are confident that those responsible for administering the referendum have the experience and resources they need to judge appropriately the likely turnout and ensure that sufficient polling stations are provided, and that the polling places are accessible and appropriately located."

The committee also backed the approach set out in the Bill which would see local results declared before the national result is announced, with MSPs saying they expected the Chief Counting Officer for the referendum to "authorise counting officers to announce local results without any unnecessary delay".

A Scotland Office spokesman stressed that the UK Government "always abides by purdah rules" but said it saw "no need" to put these on a statutory footing.

The spokesman said: "The UK Government always abides by purdah rules for all elections and referendums.

"The Prime Minister and Secretary of State for Scotland both signed the Edinburgh Agreement which commits us to following the purdah rules for the independence referendum.

"We welcome the Committee's acceptance that there is no reason to doubt the good faith of that commitment from the UK Government and we see no need to put these rules on a statutory footing."

A Scottish Government spokesman said: "The Scottish Government welcomes the committee's thorough and positive report and continued detailed consideration of the Scottish Independence Referendum Bill. We will reflect on and respond to the Report's findings as the Bill proceeds through its remaining Parliamentary Stages.

"We are pleased to note that the Committee recommends that the general principles of the Bill be agreed to and that it draws attention to the fact that the Electoral Commission has expressed confidence in the robustness of the Bill."

In their report, MSPs on the committee said they were "encouraged to hear" that the UK and Scottish Governments were having talks after the the Electoral Commission said voters should be provided with information about what would happen after the referendum, in the event of a Yes or a No vote.

The Scotland Office spokesman said: "In their report in January, the Electoral Commission said that people were asking them factual questions about the referendum and that it would be helpful if both Governments could agree to provide the answers.

"Civil servants from the UK and Scottish Governments are working together to produce written material, agreed by both Governments, that answers the questions set out by the Commission. These included whether there would be a threshold for a Yes vote, could the result be ignored or overturned, and who would be the Prime Minister the day after the referendum.

"We hope that both Governments will soon be able to finalise material to send to the Commission for their information leaflet.

"These talks between officials are in no way negotiations about independence. Both Governments are agreed that there can be no pre-negotiations."

He stressed: "UK Ministers have made it clear time after time that we will not open up negotiations or set out a contingency plan for independence. The UK Government works for the whole of the UK including Scotland, and we are deeply committed to the United Kingdom."