Britain will strip power from local Catholic and Protestant politicians within hours and resume sole responsibility for running Northern Ireland, the British governor announced Monday.

Northern Ireland Secretary John Reid said the order to suspend the authority of Northern Ireland's power-sharing administration and legislature would take effect at midnight (7 p.m. EDT) and last indefinitely. He defended his intervention as essential to prevent the collapse of the coalition, which has taken years of negotiations to forge and sustain.

"It has become clear that decisive action is needed to safeguard the progress made," Reid told reporters at Hillsborough Castle, his state residence outside Belfast.

Reid's decision followed a threat by the major Protestant party, the Ulster Unionists, to withdraw from power-sharing -- the key goal of the Good Friday peace pact of 1998 -- because of alleged Irish Republican Army spying.

First Minister David Trimble, leader of the Ulster Unionists and the local administration, had set Tuesday as a deadline for Britain to intervene.

Trimble had pressed in vain for Reid to expel Sinn Fein, the IRA-linked party, rather than to take power away from all four parties in the coalition. But Trimble said he accepted Reid's move as "a poor second best," and offered to resume cooperation with Sinn Fein if the IRA disbanded.

Four people, including Sinn Fein's top legislative aide, are behind bars awaiting trial for espionage-related charges following police raids Oct. 4. The suspects are accused of stealing documents from Reid's office that allegedly include details of potential IRA targets and records of talks between Britain and other key parties.

Reid said the accusations against Sinn Fein had damaged Protestant confidence, but kicking out any party now would be premature.

He expressed hope that negotiations in coming months would rebuild trust, particularly between the Ulster Unionists and Sinn Fein, and allow Britain to restore power to locals before elections to Northern Ireland's legislature next May.

In remarks apparently addressing the IRA-Sinn Fein movement, he emphasized, "The time has come for people to face up to that choice between violence and democracy."

Britain's move means the 108-member legislature will no longer convene. Instead Reid, a Scotsman appointed by Prime Minister Tony Blair in 2000, will oversee the administration's 12 departments with help from a beefed-up contingent of lawmakers from London.

Reid indicated he planned to consult regularly with the powerless administration's top two figures -- Trimble and the Catholic deputy leader, Social Democratic and Labor Party chief Mark Durkan -- to promote continuity and keep government disruption to a minimum.