David Cameron has given his backing to Annabel Goldie

Mr Cameron paid public tribute to leader north of the border, Annabel Goldie, and to Peter Duncan, the chairman of the Scottish party.

His praise did not extend to David Mundell, who is alleged to have made criticised them in a leaked memo.

"Annabel Goldie and Peter Duncan are doing a great job," said Mr Cameron.

He added: "Annabel has a no-nonsense approach and is addressing the issues that really matter in Scotland.

"The party in Scotland is in better health now than it has been for many years and is running an effective campaign.

Faction fighting

"I am looking forward to the Scottish conference tomorrow."

The disclosure of the purported memo threatens to overshadow the party's conference in Perth, ahead of the Holyrood elections in May.

The memo is a particular embarrassment to Miss Goldie who, when she became leader in November 2005, warned that faction fighting had to stop.

The memo lamented "the simple lack of thinkers" on Tory benches at Holyrood.

And Mr Mundell said the replacement of Scots party chairman Mr Duncan was "an immediate priority".