Rice had been stuck in the northern Iraqi city of Arbil after meetings with Kurdish officials because the plane she flew in on from Baghdad earlier in the day had engine problems, State Department spokesman Sean McCormack said.

"This aircraft had a problem with the engine and the pilot and the crew made the assessment that they did not want to use that aircraft, so they called for backup aircraft," McCormack said.

Rice and her entourage eventually boarded the second aircraft and were headed toward a US air base in Incirlik in Turkey, where her official plane is parked.

From Incirlik she was due to head for London, where she was to arrive around 1700 GMT to attend a meeting of six major powers on whether to urge the United Nations to slap sanctions on Iran over its suspect nuclear programme, McCormack said.

The Secretary of State's arrival in Baghdad late Thursday was also delayed after her C-130 military transport plane was forced to circle for 45 minutes over an airport temporarily closed by insurgent rocket attacks.