Gordon Brown yesterday launched a thinly veiled warning to Labour colleagues at Holyrood not to dance to the SNP tune on seeking extra powers for the Scottish Parli-ament as Westminster MPs fear they are being frozen out of the constitutional debate.

At his first appearance before the Commons liaison committee, made up of senior MPs, the Prime Minister was asked by Frank Doran, Labour MP for Aberdeen North, about his view on the calls for more powers for the Scottish Parliament in light of the constitutional convention proposed by Wendy Alexander, leader of the Labour group in Edinburgh.

No-one, Mr Doran pointed out, seemed to be arguing for the "status quo". Mr Brown appeared to sidestep the issue, declaring that while the debate on extra powers was "inevitable", it all depended on what was meant, stressing that it was possible to "tidy up" matters in different ways.

However, his most telling comment came when he felt the need to remind colleagues: "Sometimes people have forgotten this is devolution, this is not a form of federalism."

Ms Alexander, in Whitehall last week for private talks with colleagues, has proposed scrapping the 29-year-old Barnett formula and replacing it with powers for Scotland to set some taxes and be assigned a share of other taxes set in London. This would mean a smaller block grant based on need replacing the current one, which is based on population.

Her argument is that unless Labour develops an alternative to independence, voters might assume the Nationalist policy is the only choice on constitutional change.

Last week, Ms Alexander said: "There is a desire in Scotland for further change. Devolution is a process, not an event." However, this is not a viewed shared by some of her Westminster colleagues.

No 10 has maintained there are no plans to scrap the funding formula.