KUALA LUMPUR, Malaysia — The international search for the missing Malaysian jetliner expanded further into the Indian Ocean today amid signs the aircraft may have flown on for hours after its last contact with air-traffic control nearly a week ago.

A U.S. official told The Associated Press the Malaysia Airlines plane sent signals to a satellite for four hours after the aircraft went missing early last Saturday, raising the possibility the jet carrying 239 people could have flown far from the current search areas. It also increased speculation that whatever happened to the plane was a deliberate act.

Malaysia’s Transport Minister Hishammuddin Hussein said the search was expanding further afield, not because of any new information about the plane’s flight, but because the aircraft has not yet been found.

Malaysian officials declined to discuss when — or even whether — they had information about signals to satellites, and that they would release details only when verified. Hishammuddin said Malaysian investigators have worked with U.S. colleagues in Kuala Lumpur since Sunday.

“I hope within a couple of days to have something conclusive,” he told a news conference.

If the plane had disintegrated during flight or had suffered some other catastrophic failure, all signals — the pings to the satellite, the data messages and the transponder — would be expected to stop at the same time. Experts say a pilot or passengers with technical expertise may have switched off the transponder in the hope of flying undetected.