The Orange Order has voted to sever its links with the Ulster Unionist Party.
The decision was made during a meeting of the Grand Lodge in East Belfast
today.
Orange Order Grand Master Robert Saulters, speaking after the meeting, said: "The Loyal Orange Institution will continue to lobby for the unionist cause as events require and we will seek to establish good relationships with all those engaged in the political interests of the unionist people."
The decision to pull out of the Ulster Unionist Council effectively ends the Order's 100 years of historical ties with the party.
The links go back to the formation of the UUC in 1905.
The Order, which has been accused by nationalists of being a sectarian organisation as it does not allow Catholic members, said that while its members had been among the founding fathers of the UUC, today's motion stemmed from the current restructuring of the party which had caused Orangemen to reflect on the relationship between the parties.
Mr Saulters said: "When the UUC was established there was only one Unionist Party. That is no longer the case and we feel that arrangements made in 1905 are no longer relevant to the political scene in Northern Ireland in 2005."
The decision will please modernisers within the Ulster Unionist Party who have been trying to end the situation where Orange delegates who are not supporters of the party have a vote on the party's ruling council.
An Orange Order spokesman said that the Order had always urged its members to take an interest in politics whichever party they supported.
"As a democratic organisation we never tell our members which way to vote but we do encourage them to exercise their democratic right and cast their vote in the interests of the people of Northern Ireland."
Jim Rodgers, a UUP councillor and member of the Orange Order, said he was saddened but not surprised by the decision.
"It is a major blow just a week after we celebrated the centenary of the party.
"With public opinion polls showing us in a very bad position, it is another major setback. It is not good having people leave our party but it has been a cold house for the Orange Order for some considerable time," he added.