A senior member of the Scottish Government has warned that devolution is “under threat as never before” as he accused Tories at Westminster of taking an “increasingly interventionist approach” to politics.

Holyrood’s External Affairs Secretary Angus Robertson told MPs on the Scottish Affairs Committee that prior to Brexit successive UK governments had “generally and rightly recognised that devolved matters were the responsibility of devolved institutions”.

But he said that since the vote to leave the European Union took place in 2016 ministers south of the border had adopted an “increasingly interventionist approach into devolved policy matters”.

Mr Robertson said that had led to an “erosion of the protections provided to devolved institutions”, adding there had been a “hollowing out” of the  Sewel Convention – which sets out that the UK should not legislate in devolved areas without the consent of the devolved administrations.

Mr Robertson said: “This is something that the UK Government has decided to do, it has chosen to override the Scottish Parliament withholding consent and in many cases the Welsh Senedd not granting consent too.”

Giving evidence to the Commons Scottish Affairs Committee as it met in Edinburgh, he said the “effect of the UK Government’s actions is to constrain the powers and responsibilities of devolved institutions”.

With MPs taking evidence on the relationship between governments in the run-up to the 25th anniversary of devolution later this year, Mr Robertson said: “While there are good examples of collaboration, the simple reality is that the actions of the UK Government since 2016 especially have caused significant damage to the devolution settlement, which was established with overwhelming public support.”

While he stressed it had “not always been so”, the Scottish External Affairs Secretary added that the “position has deteriorated badly since 2016 as a consequence of Brexit, so much so that the very existence of devolved government is under threat as never before”.

He told MPs the problem was not just confined to Scotland, saying similar concerns had been raised in Wales.

Ministers in Cardiff “have the same views on the problems that are being faced by devolved administrations”, Mr Robertson said.

“This is not a Scotland-specific issue,” he added.

“It is something that is reflective of a state of mind in Whitehall, which is that the devolved administrations are to be managed, are to be put in their place.

“The bottom line is that the UK Government does not take intergovernmental relationships seriously.”

As an example of this Mr Robertson said he could provide the committee with “chapter and verse about meetings which are not attended, meetings which are cancelled” by UK ministers.

He said: “I think I am right in saying that a British prime minister has not attended a full British-Irish Council meeting since Gordon Brown did in 2010.”

Mr Robertson claimed “senior ministers” in the UK Government were not “particularly interested in having good intergovernmental relations”, adding that if they were “they would turn up”.

Speaking about the importance of relationships between ministers in Edinburgh and London, Mr Robertson, who also holds the culture brief in the Scottish Government, said: “I’m now on my fourth UK culture secretary. I think I have met one of them.

“And there have been frequent cancellations. That’s just one example of the problem at hand.”

He said that the devolution settlement had envisaged annual meetings between the UK foreign secretary and the Scottish Government’s external affairs secretary, but added: “When I met James Cleverly I was the first External Affairs Secretary to actually have a meeting in the by then 24 years of devolution, 23 years perhaps.”

Scottish External Affairs Secretary Angus Robertson said he had still to meet Foreign Secretary Lord Cameron, as he told how a scheduled meeting had been cancelled (Lucy North/PA)

Mr Robertson also said that a meeting he was “supposed to have” with current Foreign Secretary Lord David Cameron “was cancelled and no subsequent date has yet been found for that”.

Speaking about the situation generally, Mr Robertson said that “more often than not” letters from Scottish ministers asking for meetings “aren’t even replied to”.

He added that “that’s the norm, unfortunately, with things”.

Mr Robertson told the committee the “significant churn in Whitehall of ministers” could be a reason for this, saying ministers were sometimes “not in office for very long” and may not understand “why things like this really matter”.

But he insisted this approach came “from the top down”, telling the committee: “Across the piece, from the top down, there has been an aversion to meeting with opposite numbers.”

A UK Government spokesperson said: “Citizens rightly want their governments working together to deliver for them and that is why the UK Government is committed to close intergovernmental working. Both ministers and officials meet regularly with counterparts.

“In 2023, there were over 200 ministerial meetings between the UK and devolved governments, addressing key issues, including tackling cost-of-living pressures, improving NHS waiting lists, and delivering for people across the UK through the freeport and investment zone programme.”