The UDP constituency associations in Co Antrim and East Derry yesterday confirmed it had split from the party in order to pursue an anti-agreement strategy. The split comes as more Catholic homes in Larne, Co Antrim, were attacked.
Mr Gary McMichael, the leader of the UDP, which is linked to the UDA, said he regretted the departure of an estimated 100 members, about one-third of the party.
He said a statement could be issued by the UDA as early as today and it was "not expected to be negative" regarding the peace process.
Mr Tommy Kirkham, a leading party figure in Co Antrim who called for a hardening of position against the Agreement, said the party was too small to accommodate their views.
The former UDP members intended to run independent unionist candidates in the next local elections.
Mr Kirkham has denied UDA involvement in the recent spate of sectarian attacks.