Alex Salmond is considering a move north

But Mr Salmond, who led the SNP for a decade, denied he had any intention of challenging Mr Swinney's leadership on his return north.

He said Mr Swinney always knew of his intention to return to the Scottish Parliament at some stage.

"John Swinney knew about my wish to return and he fully supports it," he said.

"It was decided last year when I went to Westminster to help the SNP group. I am a strong supporter of John Swinney's leadership and any suggestion that I would be a threat is ludicrous."

'Caretaker leadership'

Mr Salmond added that he would prefer to serve in the north east of Scotland on his return, as that felt like his "political home".

"It's not up to me to say I will do this or that. It is up to the constituencies to decide who they want and then for the people to elect them."

But Labour's parliament minister, Patricia Ferguson, said Mr Swinney's return would not be good news for the present SNP leader.

She said: "While John Swinney has made a failure of his caretaker leadership, Alex Salmond has been looking for a hobby in his retirement.

"He obviously thinks leading the SNP in the Scottish Parliament will be a diverting way to take up some spare time. He is wrong.

John Swinney succeeded Alex Salmond in 2000

"Representing the people of Scotland is about delivering on their priorities: health, education, transport, jobs and crime, not about bouncing from one parliament to another on a whim."

Mr Salmond has represented the Banff and Buchan constituency since 1987.

His political opponents seized on his decision to quit the Scottish Parliament and represent the nationalists at Westminster.

They claimed the move represented a major u-turn, since Mr Salmond had indicated he did not want to go back to the House of Commons.

However, Mr Swinney said he wanted his predecessor to stay in the Commons because of his "substantial experience".

At the time, Mr Salmond said he was proud to have played a part in the creation of a Scottish Parliament, but felt after 10 years in charge, the time was right to represent the SNP at Westminster.