SINN Féin collapsed the Stormont executive so the party could use Brexit to further the cause of a united Ireland, former first minister David Trimble has claimed.
The one-time Ulster Unionist leader said the UK's decision to leave the EU was the "real reason" why the institutions had foundered.
Lord Trimble called on the British government to put pressure on Sinn Féin by cutting financial support to its abstentionist MPs.
The party last night rejected the claims and accused the Tory peer of being "out of touch".
New secretary of state Karen Bradley is to hold further meetings with the Stormont parties this week ahead of any bid to restart talks aimed at restoring devolution.
Department of Finance officials warned last month that for an "effective budget" to be set and delivered by a new executive, it would need be agreed in early February.
However, with the West Tyrone by-election triggered by Barry McElduff's resignation expected to take place in March, it is possible negotiations would be put on hold during what could be an acrimonious campaign.
Speaking on Sky News yesterday, Lord Trimble said the British government needed to adopt a new approach.
He said the appointment of a new secretary of state created an "opportunity to rethink".
"Their (British government) business about 'oh we must have talks' is effectively saying to the electorate in Northern Ireland that Sinn Féin matters more than any other party," he said.
"I think the government should change its position, and because Sinn Féin caused the problem then Sinn Féin should carry some of the burden."
The former Upper Bann MP claimed the British government should "seriously consider" withdrawing allowances for Sinn Féin's abstenionist MPs.
He said the Prime Minister Theresa May and Taoiseach Leo Varadkar should get involved in attempting to secure a deal to restore devolution "when the circumstances are right".
"But you've got to bear in mind that the experience is that the republican movement only moves under pressure," he said.
"It doesn't matter how strong your arguments are, they're prepared to hunker down and wait until the time is right for them."
Lord Trimble argued that Arlene Foster alone should not bear responsibility for the RHI scandal as every minister in the executive signed off what he described as a "very bad" programme.
"In my view... the real reason why Sinn Féin acted the way they did is because they wanted to be out of office and to use Brexit as an issue to attack the British government and hope to get a increase in support for them to advance their basic project further," he said.
"So that is an underlying factor but it doesn't take away from the fact that it was Sinn Féin that collapsed the assembly and there's no reason to believe they'll restore it out of the goodness of their heart. It'll require pressure."
A Sinn Féin spokesman last night said: "The executive was suspended four times during David Trimble’s tenure as first minister so it’s a bit rich for him to be lecturing others.
"It also demonstrates how out of touch he is if he believes citizens should simply ignore the denial of their rights and the fact that the RHI scandal happened under the watch of successive DUP ministers."
