Home Secretary Theresa May has waded into the row over scandal-hit Police Scotland attacking the Scottish Government's handling of the force.

The Tory minister, tipped as a potential successor to David Cameron, warned that Scotland single police service had suffered "real operational problems".

And she said that the difficulties that have befallen the force were a warning to others across the UK.

But a spokesman for Scottish Justice Secretary Michael Matheson accused Mrs May of "rank hypocrisy" over her comments.

The Home Secretary has faced staunch criticism from police leaders south of the border following a series of controversial reforms and a stark fall in officer numbers.

Police Scotland is currently facing questions over its investigation into the leak of confidential details of a murder inquiry to a newspaper.

Over the last year it has faced a number of scandals and lost its Chief Constable Sir Stephen House.

In July, Police Scotland officers failed to respond to reports of a car crash near Stirling.

Lamara Bell lay in the car next to the body of her dead boyfriend John Yuill for three days and later died of her injuries

The police watchdog is also investigating the case of Sheku Bayoh who died after being restrained by officers in Kirkcaldy.

Last year the force was also forced to U-turn on its policy to allow officers to be armed on routine duties.

Earlier this week John Swinney announced an extra £55million for the force in his Budget.

But a report released yesterday by the Auditor General warned that policing in Scotland could face a funding gap of almost £85 million by 2018/19.

Meanwhile, a new report from HM Inspector of Constabulary Derek Penman found that had Police Scotland had "major financial challenges" and morale among officers and staff was mixed.

Mr Swinney has repeatedly asked Mrs May's government to make Police Scotland exempt from its around £30m VAT bill - as the old eight forces were.

At a briefing for journalists at Westminster Mrs May said: "I think the way that Police Scotland has been brought together shows that one should be very wary and careful about the ideas of those who say that forming a single police force or a larger police forces is the answer to everything.”

She added that there had been some “real operational issues” for the force.

And, in a criticism of the role of Scottish ministers, she said: “I think I am also right in saying that they still have yet to put forward a proper business case for doing it."

In September, before the latest 'spying' row began, Mrs May also hit out at Scotland's single police force saying it was "already facing difficulties" and that "top down restructuring" did not make the savings it promised.

Today another cabinet minister, David Mundell, also accuses the SNP of being the "most centralising" government Scotland has ever had, ahead of a speech on devolution on Monday.

A spokesman for Scottish Justice Secretary Michael Matheson: “This is another of example of rank hypocrisy from the Tories.

"Theresa May and her party are presiding over a total collapse in police numbers south of the border, which are predicated to fall by a further 20,000 – on top of the 16,000 already lost.

"In contrast, the SNP Government have maintained 1,000 additional officers in the face of Westminster cuts, helping crime in Scotland to fall to a 41-year low.”

Mrs May, who has been in charge of the Home Office, traditionally seen as a political poisoned chalice, since the Conservative Government came to power in 2010, also said that she was having talks with European counterparts about UK proposals to change the definition of 'asylum seeker',

The move follows her polarising and heavily criticised speech to the Conservative party conference in October.

Mrs May said she was disappointed by reaction to the speech and felt that her call for the UK to crack down on bogus cases in order to help greater numbers of asylum seekers had been lost amid the controversy.

She also hit out at Donald Trump, labelling the US tycoon, currently in the race to become the Republican nominee in next year’s US Presidential election, “divisive”.

But she refused to be drawn on calls for her to ban him from the UK for hate preaching following his claims that Muslims should be prevented from entering the US.

Earlier this month Mr Trump called for a ban on Muslims entering the US in the wake of recent terror attacks.

Mrs May said: "His comments were divisive and unhelpful. And his comments about policing here in the United Kingdom were totally wrong.

"And I think that what is important for politicians who are looking at these issues to actually to try to work to bring communities together, to encourage cohesion rather than to divide people”.