Thailand's Constitutional Court has ruled that Prime Minister Srettha Thavisin be removed from office over his appointment of a Cabinet member who was convicted in the past. His dismissal may lead to a political upheaval in the country.

The court ruled on Wednesday that appointing such a person to the Cabinet was a violation of the constitutional ethical standards.

Srettha appointed former Prime Minister Thaksin Shinawatra's lawyer to the position in April. The court began examining a petition that conservative former members of Senate submitted after the appointment, calling for Srettha's dismissal.

Some local media outlets report that the ruling represents a pressure from the conservative establishment against Srettha's Pheu Thai Party. The party had been at odds with pro-military conservative forces, but they formed a coalition government.

The parliament is to choose a new prime minister to fill the vacancy. Observers say political turmoil is likely in the process.

As recently as August 7, the Constitutional Court dissolved the Move Forward Party, the largest pro-democracy opposition party, over the party's campaign to amend a law banning defaming the royal family.

The court had often given judgment in favor of the military and conservative forces, raising doubts about its fairness.