A no-deal Brexit would risk taking the Union to "breaking point", a leading think-tank has warned.

The Institute for Government[IFG] claimed that since Boris Johnson became Prime Minister in July there had been a decline in engagement with the Scottish Government.

In a report, No-deal Brexit and the Union, it declared: "A no-deal Brexit would be a high stakes gamble with the future of the Union."

The authors said short-term no-deal planning had diverted attention away from longer-term questions about the relationship between Westminster and devolved governments.

READ MORE: UK and EU close in on Brexit deal as fears raised over risk to Union

The IFG said meaningful and systematic engagement between them would be necessary for negotiations on future international agreements, including the UK-EU relationship and other trade deals.

"No-deal will mean no transition period, so these unresolved issues will need to be addressed urgently, in what will be an even more charged political atmosphere," the report explained.

The think-tank argued a no-deal Brexit would "increase the risks faced by the Union itself", adding: "In Northern Ireland, no-deal and direct rule would make a swift return to power-sharing unlikely. Pressure for a border poll on the island of Ireland is likely to increase."

The report went on: "Brexit has put a strain on relations between the nations of the UK. A no-deal departure from the EU could take it to breaking point.

"The Scottish and Welsh Governments have felt increasingly side-lined since 2016 and, aside from the DUP, voices from Northern Ireland have been unrepresented in the Brexit process.

"While the devolved administrations have been vocal in their opposition to leaving the EU without a deal, the UK Government has committed to leaving the EU on October 31 'come what may'. This runs counter to the Prime Minister's commitment to strengthen the Union."

IFG senior fellow Akash Paun said: "The UK Government needs a new strategy to make the positive case for the Union and improve its approach to working with the devolved governments."

READ MORE: Nicola Sturgeon says indyref2 'must happen'

Scottish Labour MP Martin Whitfield, on behalf of the pro-EU Best for Britain campaign, said: “Boris Johnson is not only gambling with the economy and people’s livelihoods, he is gambling with the Union.

“He has repeatedly been warned about the threat of a no-deal Brexit to the integrity of the UK but he refuses to listen.

“To help preserve the Union and protect the British economy he should take a no-deal Brexit off the table and allow the people of the UK a final say with the option to remain in the EU,” added the East Lothian MP.