Image copyright Getty Images Image caption David Cameron, Nick Clegg and Ed Miliband have decided to campaign in Scotland ahead of the referendum

The main UK party leaders are visiting Scotland to campaign against independence, ahead of the referendum.

Prime Minister David Cameron and Labour leader Ed Miliband will abandon their weekly Prime Minister's Questions clash and instead fly north on Wednesday.

It came as the Scottish pro-Union party leaders announced their backing for more powers for Scotland.

First Minister Alex Salmond said the campaign to keep the Union was now in "absolute panic".

iberal Democrat leader and Deputy Prime Minister Nick Clegg will also be campaigning in Scotland, ahead of the 18 September referendum, although the three leaders will not travel or appear together.

Image copyright Getty Images Image caption United: Tory Ruth Davidson, Labour's Johann Lamont and the Lib Dem's Willie Rennie

In a joint statement they said: "There is a lot that divides us - but there's one thing on which we agree passionately: the United Kingdom is better together."

The visit was announced on Tuesday after polls indicated a narrowing of the lead that the pro-Union Better Together campaign has over the pro-independence Yes Scotland campaign.

In their statement, the UK leaders emphasised that keeping the UK together was now their priority, adding: "That's why all of us are agreed the right place for us to be tomorrow is in Scotland, not at prime minister's questions in Westminster.

"We want to be listening and talking to voters about the huge choices they face. Our message to the Scottish people will be simple: 'We want you to stay.'"

In their statement, the UK leaders emphasised that keeping the UK together was now their priority, adding: "That's why all of us are agreed the right place for us to be tomorrow is in Scotland, not at Prime Minister's Questions in Westminster.

"We want to be listening and talking to voters about the huge choices they face. Our message to the Scottish people will be simple: 'We want you to stay.'"

William Hague will stand in for Mr Cameron at Prime Minister's Questions at Westminster, while Harriet Harman will deputise for Mr Miliband.

The announcement came as the leaders of Scottish Labour, the Scottish Conservatives and Scottish Liberal Democrats stood shoulder-to-shoulder to endorse a timetable to deliver more financial and other powers for Scotland, in the event of a referendum "No" vote.

Johann Lamont, Ruth Davidson and Willie Rennie backed the plan of action spearheaded by former prime minister Gordon Brown, which would see work to begin on the plan on 19 September, the day after the referendum.

Reacting to news of Wednesday's visit, Mr Salmond said: "The 'No' campaign is in complete and utter disarray, and they are making this farce up as they go along.

Image copyright Getty Images Image caption First Minister Alex Salmond said the campaign for the Union had fallen apart

"Together, David Cameron, Ed Miliband and Nick Clegg are the most distrusted Westminster politicians ever - and their collective presence in Scotland will be another massive boost for the 'Yes' campaign.

"The message of this extraordinary, last minute reaction is that the Westminster elite are in a state of absolute panic as the ground in Scotland shifts under their feet."

Mr Salmond added: "While 'No' continue to get it badly wrong, 'Yes' will continue with a campaign that is energising Scotland and galvanising support the length and breadth of the country."

In other developments....

Media playback is unsupported on your device Media caption It took two goes to raise the Saltire flag in Downing Street

A Buckingham Palace spokesman has said: "Any suggestion that the Queen would wish to influence the outcome of the current referendum campaign is categorically wrong." The BBC understands the statement was in response to press reports of calls for the Queen to speak out in favour of the union. The Palace insisted the referendum was "a matter for the people of Scotland".

First Minister Alex Salmond has said the Queen "will be proud" to be the monarch of an independent Scotland. He dismissed press reports that Her Majesty was concerned about the prospect of Scottish independence.

Labour leader Ed Miliband has urged Labour councils to fly the Saltire to show their support for Scotland remaining in the Union. He joined the Mayor of Liverpool, Joe Anderson, to fly the Scottish flag from a council building in the city. The flag was also raised over Downing Street.

Bank of England governor Mark Carney has told the TUC that currency union in the event of Scottish independence would be "incompatible with sovereignty". But the SNP said currency union was "in the best interests of both an independent Scotland and the rest of the UK".

On the campaign trail in Scotland, Deputy First Minister Nicola Sturgeon joined anti-poverty campaigner and Labour member Bob Holman in the east end of Glasgow, where she insisted a "Yes" vote could create a fairer Scotland. Mr Holman took UK Work and Pensions Secretary Iain Duncan Smith around Easterhouse in 2002, when the Conservative MP was leader of his party.

Better Together leader Alistair Darling was joined by First Minister of Wales Carwyn Jones, who made a speech in Edinburgh about the benefits of devolution within the UK.

MPs in Westminster are poised to launch an inquiry into devolving more powers to England, Wales and Northern Ireland. The Political and Constitutional Affairs Select Committee will examine extending some of the powers granted to Scotland - in the event of a No vote - to the rest of the UK.

Why did the words of bank boss Mark Carney leave one BBC editor scratching his head? (Well, for a while anyway) Find out in our referendum round-up of the day.