Prime Minister Prayut Chan-o-cha faces the prospect of being taken to the Constitutional Court over his allegedly unlawful occupation of an army residence.

Prasert Chanthararuangthong, a Nakhon Ratchasima MP for the main opposition Pheu Thai Party, told parliament during Wednesday's censure debate that Prayut's tenancy of the army house constituted a conflict of interest.

The MP said Prayut, who is also defence minister, should have moved out of the house when he retired as army chief on Sept 30, 2014 and that by staying on free of charge he defied army regulations, which disqualified him as prime minister.

"It should not be up to the army chief to decide who gets to remain in military houses beyond their retirement," Mr Prasert said.

The other armed forces have fixed deadlines for vacating military accommodation. Navy officers must vacate within 90 days of retiring while air force officers must leave seven days before retirement, according to Mr Prasert. Water and electricity charges at Prayut's army house amounted to an estimated one million baht since he retired, he added.

He said Prayut had disregarded the regulations and he planned to petition the Constitutional Court to remove him as prime minister.

Prayut declined to comment on the allegation.