Blair warns Iran of "different phase"

By Paul Hughes

LONDON (Reuters) - Britain's British Prime Minister Tony Blair warned Tehran on Tuesday of a "different phase" if it did not free 15 British military personnel captured in the Gulf four days ago.

The sailors' capture and new U.N. sanctions imposed on Tehran on Saturday over its disputed nuclear program have stoked tensions between the West and Iran and pushed oil prices to a 2007 high.

Russia and the United Arab Emirates on Tuesday urged Iran to comply with U.N. demands that it halt sensitive nuclear work but Tehran says the U.N. resolution is illegal.

Iran, which denies any intention of making atomic weapons, has said it may charge the two boatloads of British sailors and marines with illegally entering its waters in the northern Gulf. Britain insists they were operating in Iraqi waters.

"What we are trying to do ... is to pursue this through the diplomatic channels and make the Iranian government understand these people have to be released and that there is absolutely no justification whatever for holding them," Blair said.

"They have to release them. If not, then this will move into a different phase," he told Britain's GMTV television.

Blair's spokesman said the next step London could take would be to publish proof, in the form of global satellite positioning (GPS) records, that the sailors had not entered Iranian waters.

"We so far haven't made explicit why we know that because we don't want to escalate this," he said.