Democratic Unionist Party (DUP) leader Ian Paisley said there was "no prospect of an executive including Sinn Fein/IRA for the foreseeable future".
"In keeping with our manifesto commitments, the DUP will not countenance an executive in Northern Ireland that is inclusive of those who are not committed to explicitly peaceful and democratic means," Mr Paisley told reporters.
The comments by the veteran 79-year-old hardliner appear to dash all remaining hopes that his party might again share power with Sinn Fein.
The Northern Ireland Assembly and Executive were created in 1998 under the Good Friday Agreement, and involved Protestant and Catholic parties sharing power.
But the Assembly and Executive were suspended in October 2002 after allegations of a spy ring involving the Irish Republican Army (IRA) in Belfast's Stormont parliament building and a breakdown in trust.
Charges against three IRA members accused of spying at Stormont were later dropped and one of them admitted to spying for the British.
A series of attempts by the British and Irish governments to resurrect the Assembly has failed, but hopes were given a boost last year by the IRA's decision to disarm.
In July, the IRA pledged to halt forever its armed campaign to end British rule in Northern Ireland and destroy all its weapons stocks, a move confirmed by independent observers.
However, Mr Paisley and the DUP have remained deeply sceptical, insisting the IRA is still involved in terrorism and other criminal activity.
The DUP will next week put forward an alternative plan to the British government, which resumed direct rule of Northern Ireland after the assembly was suspended, to return to devolution, but it will not include power-sharing with Sinn Fein.
Sinn Fein’s Pat Doherty says the only way forward is through the Good Friday Agreement, the BBC reported on its website.
"The DUP cannot be allowed to continue to block forward movement towards the re-establishment of the political institutions,” Mr Doherty was quoted as saying.