The pressure on Gordon Brown intensified further today as it emerged that a Government minister is on the brink of resigning because of his unhappiness with the Prime Minister's leadership.

David Cairns, Minister of State at the Scotland Office, believes Mr Brown is showing a lack of leadership and direction to the country, a source has told The Times.

Mr Cairns - who helped to coordinate the Government's disastrous Glasgow East by-election - is a close ally of one of the rebel ringleaders, former Government Whip Siobhain McDonagh, having worked as her assistant before entering Parliament as MP for Inverclyde.

He was not answering calls today, but a colleague who has spoken to him in the last 24 hours said: "He is very unhappy and has been for some time but then again he is not the only one.

"He is unhappy about the lack of direction and believes the leadership is all over the place and making lots of mistakes. He has been unhappy for some considerable time and could decide to go today."

Downing Street sources and a source close to Des Browne, the Defence Secretary, said today that Mr Cairns had not informed them that he intended to resign. Mr Cairns was, meanwhile, refusing all attempts by the press to raise him and has issued no statement to end the speculation.

Inverclyde MP Mr Cairns, a former Catholic priest, became a minister at the Scotland Office in 2007.

Mr Cairns, 42, served as a Catholic priest before entering politics, becoming a director of the Christian Socialist Movement. In 1997, he became a research assistant to Ms McDonagh and became an MP in 2001. He is a former councillor for the London Borough of Merton.

He was only able to become an MP thanks to the change in an 1801 law which barred former Catholic clergy from becoming MPs. Without the House of Commons (Removal of Clergy Disqualification) Act 2001, Cairns would never entered parliament.

More than 10 Labour MPs have asked for leadership nomination papers to be sent out to all their colleagues ahead of the Labour conference in Manchester this weekend, a move which they believe would increase the chances of unseating Mr Brown. Labour's National Executive Committee today refused to adhere to their demands.

“The Labour Party national executive committee is in agreement that internal procedural debates will not divert the Labour Party from our mission of building a fairer Britain and helping people through these challenging times," a statement released by the NEC chair Dianne Hayter said.

“The NEC fully endorses the view of the Labour Party’s general secretary and the party’s independent legal advisers.

“A leadership election when in government can only be held if requested by a majority of party conference on a card vote. Only Labour MPs can trigger the process and the NEC is confident that most MPs know their responsibilities under the rules.

“The Labour Party has followed this procedure for 11 years, as long as we have been in government under these present rules, and it has not required the issue of nomination forms at any time.

“The NEC has a responsibility to ensure the party follows these long-standing procedures and we will do so. The Labour Party will not waver from its historic responsibilities to our country and to those in greatest need.”

Heavyweight Cabinet ministers have gone on the offensive in support of Mr Brown in recent days, with Chancellor Alistair Darling leading the way.

Mr Brown was today chairing a lengthy meeting of the Cabinet and putting the final touches to a conference document - bound to be seen as a mini-manifesto - which is expected to be released this afternoon.

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