The ministers were flying to Chiang Mai to meet Prime Minister Somchai Wongsawat after anti-government protesters seized a second Bangkok airport, effectively isolating the capital from the rest of the world.
'About 30 minutes after take-off, the C-130 aircraft reported that the third engine had a problem,' Group Captain Montol Suchookorn, a spokesman for the Royal Thai Air Force, told AFP.
'The pilot decided to return to Bangkok and asked for an emergency landing,' he said.
'There was a successful landing but mechanics failed to fix the engine, so ministers took off in other smaller aircraft belonging to state agencies.' Most of the other planes had now landed safely in Chiang Mai, he said.
Mr Somchai said in a televised address to the nation on Wednesday night that he had called the meeting in Chiang Mai to map out 'measures' to cope with the growing protests.
He also rejected a call from the powerful army chief to dissolve parliament and call new elections in a bid to end months of unrest that has paralysed the country.
The premier arrived in Chiang Mai on Wednesday after his flight home from an APEC summit in Peru was diverted because demonstrators had occupied Bangkok's Suvarnabhumi international airport.
Protesters seized the old Don Mueang airport, now used for domestic flights, early Thursday.
They said they planned to block the runways at Don Mueang, which are also used by the military, to stop the ministers from leaving but they were kept away by a heavy contingent of soldiers. -- AFP