A top Thai court on Thursday agreed to consider a case seeking to oust Prime Minister Srettha Thavisin over his appointment of a cabinet minister with a criminal conviction.

The Constitutional Court accepted a petition to remove Srettha from office, which was submitted by 40 senators under ethics rules, but it rejected an application to suspend him from his duties as prime minister while it considers the matter.

The case centres on Pichit Chuenban, appointed as a minister in a recent reshuffle, who served six months in jail for a contempt of court conviction in 2008.

Pichit, a former lawyer with close links to billionaire ex-prime minister Thaksin Shinawatra, resigned from his cabinet role on Tuesday in a bid to protect Srettha.

Judges voted 6-3 to accept the petition and gave Srettha 15 days to respond to the case.

The 250 current members of the Thai senate were appointed by the junta that ruled the kingdom after a 2014 coup.

An election to choose new senators will be held over three rounds next month.

The senate played a crucial role in determining the outcome of last year's general election, blocking Pita Limjaroenrat, whose Move Forward Party won the most seats, from becoming prime minister.

Instead Srettha, of Thaksin's Pheu Thai party, formed a coalition government with army-linked parties.