PATTAYA, March 11 (Agencies) : There was still no trace of the missing Malaysia Airlines plane on Tuesday, a day after authorities questioned travel agents at a beach resort in Thailand about two men who boarded the flight with stolen passports, part of a growing international investigation.

Three days after the plane with 239 people on board vanished from radar screens between Malaysia and Vietnam, the search effort by at least 34 aircraft and 40 ships was being widened to a 100-nautical mile (115-mile, 185-kilometer) radius from the point the plane was last detected.

Five passengers who checked in for flight MH370 didn't board the plane, and their luggage was removed from it, Malaysian authorities said. Malaysian transport minister Hishammuddin Hussein said this also was being investigated, but he didn't say whether this was suspicious.

Two of the passengers were traveling on passports stolen in Thailand and had onward tickets to Europe, but it's not known whether the two men had anything to do with the plane's disappearance. Criminals and illegal migrants regularly travel on fake or stolen documents.

Hishammuddin said biometric information and CCTV footage of the men has been shared with Chinese and US intelligence agencies, which were helping with the investigation. Almost two-thirds of the passengers on the flight were from China.

The stolen passports, one belonging to Christian Kozel of Austria and the other to Luigi Maraldi of Italy, were entered into Interpol's database after they were taken in Thailand in 2012 and 2013, the police organization said.

Electronic booking records show that one-way tickets with those names were issued on Thursday from a travel agency in the beach resort of Pattaya in eastern Thailand. Thai police Col. Supachai Phuykaeokam said those reservations were placed with the agency by a second travel agency in Pattaya, Grand Horizon.

Thai police and Interpol officers questioned the owners. Officials at Grand Horizon refused to talk to The Associated Press.