British Prime Minister Tony Blair warned Northern Ireland's feuding political parties on Thursday that failure to resolve a row over policing could wreck plans to restore Protestant-Catholic power sharing in the province, Reuters reported. Blair, who cut short a holiday in the United States to intervene in the latest stand-off between nationalist Sinn Fein and its pro-British opponent, the Democratic Unionist Party (DUP), said both sides must honour their commitments. Sinn Fein must support policing and the rule of law in the British-ruled province and the DUP must reciprocate by agreeing to share power after an election planned for March 7, he said. "It is only on this basis and with this clarity that we can proceed to an election," he said in a statement. Blair flew home after failing to resolve the dispute over policing in a series of telephone calls with party leaders. It is one of the last obstacles to the planned restoration in March of a Belfast-based, power-sharing assembly suspended since 2002.