Gordon Brown declared support for a replacement deterrent

The man tipped to succeed Prime Minister Tony Blair said he wanted to replace the Trident missile system.

That has focused attention on the future of the Faslane naval base, home to submarines which carry the weapons.

The SNP called on Jack McConnell to outline his position but he said the issue should be subject to debate.

During first minister's questions on Thursday, SNP deputy leader Nicola Sturgeon asked Mr McConnell repeatedly to declare his position with regard to his senior Labour colleague's stance and accused him of dodging the question in his responses.

She said: "What I am asking the first minister is what side of that debate he starts from - does he agree with Gordon Brown that we need new nuclear weapons, or like many in his own party will he oppose new weapons of mass destruction on the Clyde?"

Mr McConnell told her: "The easy answer in these situations would, as ever, be yes or no. But I think this is an issue which requires a considered opinion.

FASLANE HISTORY Acquired by the Ministry of War and Transport in 1940 WWII saw increased naval presence at the base The UK's first nuclear-powered attack submarine arrived in 1963 The base grew quickly after the decision to purchase Polaris missiles The first of four Polaris submarines arrived at Faslane in 1967 Preparations began for the arrival of Trident missile submarines in the 1980s The base was given a wider role with the arrival of surface patrol vessels in the 1990s The first submarine armed with the Trident missile system arrived in 1996

"I welcome the UK Government's commitment to a debate on that issue, and I hope it is an informed and sensible debate - on the one hand, without committing ourselves automatically to a new generation of nuclear weapons."

Reaction at Westminster has been mixed among Mr Brown's party colleagues.

North Ayrshire and Arran Labour MP Katy Clark, an opponent of nuclear weapons, said the party leadership must stick to its commitment to debate the issue and should move to a "non-nuclear defence strategy".

She told BBC Radio Scotland: "I very much hope it's not a decision that's already been made. We've been told repeatedly in the parliamentary Labour party that the decision hasn't been made as yet.

"When we got the current Trident system in 1980, the Conservatives didn't have any discussion in parliament about whether we actually decided to commission that generation of nuclear weapons which, of course, arrived in Scotland in 1994."

Fellow Labour MP Eric Joyce said he was certain there would be a "meaningful debate".

Jack McConnell said there should be a "sensible debate"

Mr Joyce, a former Army officer who represents Falkirk, said the UK continued to face the same potential threats as in the past.

He said: "At root, I think the debate will probably be based around the issue of proliferation. We haven't constrained proliferation yet and in some ways it continues unabated.

"While it may seem like an issue on the cusp - the renewal of Trident - the fact is that we've got much more proliferation than we had when we bought Trident in the first place."

Scottish Green MSP Chris Ballance said: "The message from Brown is clear and is cloned directly from Blair: he intends to break international law, make a decision first and pretend to hold a 'balanced' debate across the country later."

Church leaders in Scotland have branded the pro-nuclear position "immoral".

The Right Reverend Alan McDonald, Moderator of the General Assembly of the Church of Scotland, said: "There can be no place for weapons of mass destruction in a world that God loves so much."

Cardinal Keith O'Brien, Scotland's most senior Catholic, said: "Since it is immoral to use weapons of mass destruction in an act of war, equally, storing, accumulating and replacing them far from eliminating the causes of war actually risks aggravating them."