LORD Robertson, a former UK defence secretary and the outgoing secretary-general of Nato, has been called upon to help arbitrate on the fate of Scotland's threatened infantry regiments.

He is likely to chair the last meeting of the council of Scottish colonels before a recommendation on which of the six battalions will be axed goes to Brigadier Robbie Scott-Bowden, the Ministry of Defence director of infantry.

The move will also allow Lieutenant-General Sir Alistair Irwin, the current chairman, to stand down to avoid accusations of favouritism. He is also honorary colonel of the Black Watch.

There have been calls for General Irwin's resignation after The Herald revealed last week that he had written a paper advocating the end of the current regimental system while he was supposed to be fighting the Scottish division's corner in Whitehall.

He submitted the paper to the executive committee of the army board, its governing body, in his capacity as adjutant-general while his own regiment, the Black Watch, was still fighting in Iraq last year.

The regimental associations are collecting questionnaires that were sent to all serving and former members of the six regiments involved - the Black Watch, the Highlanders, the King's Own Scottish Borderers, the Argyll and Sutherland Highlanders, the Royal Highland Fusiliers and the Royal Scots - asking for their views.

The MoD would not confirm Lord Robertson's participation in the process, but a spokesman admitted that if the colonels could not agree among themselves, then the decision could ''go to independent arbitration''.

Insiders say it is unlikely they will reach a consensus on which one is to march into history.

Although he has yet to be be approached on a formal basis, Lord Robertson has let it be known he would be happy to help. He said last night: ''If I'm asked to help I will help.''

The radical changes to the army's infantry structure, cutting the number of battalions from 40 to 36 and grouping them in 15 large regiments to save money for hi-tech weaponry, was announced in July by Geoff Hoon, defence secretary.

One Scottish regiment is to be among the casualties. The council of colonels also has to decide whether the survivors are to be organised into large Highland and Lowland regiments or amalgamated into a single ''super-regiment'' covering the whole of Scotland.

The council meets to review its options on October 4, with a final recommendation due to be submitted by November 5.

There has been powerful behind-the-scenes lobbying for the formation of a three-battalion Highland regiment and a two-battalion Lowland unit, despite the fact that the vast majority of recruits come from the Lowlands and the Central Belt.

Insiders say the Royal Scots, the senior but least well recruited Lowland battalion, and the Black Watch, the senior Highland formation, have been pressing for the two-regiment solution in the expectation that they will dominate whatever emerges from the restructuring.

The parliamentary battle to save Scotland's regiments began yesterday when the SNP drew up a House of Commons motion calling on the government to abandon the shake-up.