The former Northern Ireland first minister David Trimble said a yes vote in the Scottish referendum would inevitably intensify pressure for a similar vote on Northern Ireland's future, further polarising Ulster's sectarian politics.

The politician, now a Tory peer, said he thought Sinn Féin would press for a referendum on Northern Ireland's future in the UK, arguing that a Scottish yes vote "means the union becomes a live issue again in the province," and that the issue would become the centre piece of the 2015 election campaign.

He said that come that election the subject would become "the main issue will be a referendum in the province like the Scots had – oddly enough, I think Peter Robinson [Northern Ireland's current first minister] will also seize the issue and get the unionist electorate energised and fired up to get out and vote".

Trimble predicted that an Ulster referendum would produce a higher majority to stay in the UK than any no vote in Scotland.

But he added: "The problem with all of that is that Ulster politics is going to go into the deep freeze as a result of all that. It will polarise and further divide like never before, so we won't see any progressive change in politics for at least a decade."

The Conservative peer said that was critical of the strategy of the no campaign in Scotland and it was clear that the outcome on 18 September was "going to be very tight".

He also said he would have preferred it if the Orange Order in Scotland had got their pro union rally over early in the campaign, but added that he was not in any position to call on them to cancel Saturday's mass demonstration in Edinburgh.

"There is a lot to be said for 'safety first' in the situation unionists find themselves in, Scotland but I would be inclined to leave it to the people in the Grand Lodge of Scotland, who are capable people with their heads screwed on."

On Tory MPs who are secretly hoping for Alex Salmond to triumph Thursday week, Trimble said: "They are privately wanting this not just because it would rob Labour of about 40 seats in the next House of Commons.

"Many of them see the financial benefits of this for England because once Scotland is gone then the state subvention from London is gone.

"By the way the vote doesn't decide anything regarding the state of Scotland if it is yes. Alex Salmond has been very careful to get into details about what he is going to negotiate about.

"If it's a yes vote then it is certainly not in David Cameron's interest to give Salmond what he wants, far from it.

"If there is no union then why should the English pay, why would the English electorate agree to let Scots share their currency?"

Trimble was awarded the Nobel peace prize, along with John Hume, for his role in bringing about the Good Friday Agreement in 1998.

But his backing for the peace accord that laid the foundations of a new devolved power-sharing government in Belfast badly divided the Ulster Unionist party he then led; ultimately it was displaced as the leading force in unionism by the Democratic Unionist party.

After losing his Upper Bann seat in the 2001 general election, Trimble moved to London and was appointed to the Lords.