Thai Prime Minister Prayut Chan-o-cha said Thursday he will take sole responsibility for failing to recite the full oath of allegiance when he and his Cabinet were sworn in last month.

Prayut and 35 Cabinet ministers pledged their loyalty to King Maha Vajiralongkorn in an official ceremony at the Dusit Palace in Bangkok on July 16 but failed to complete the full oath of allegiance as required by the Thai constitution.

According to Section 161 of the constitution, the prime minister and Cabinet ministers are required to swear loyalty to the king and to perform duties for the benefit of the country and the people.

Public footage of the ceremony shows Prayut, who was reading from a piece of paper, and his Cabinet omitting the last sentence of the oath about upholding and complying with the constitution.

"I want to take sole responsibility," Prayut said Thursday at the start of an official meeting televised by state ­media.

"I am concerned about what to do in order to work, to make everyone continue to work. We have to see what the constitution says but this government will continue to function," Prayut said. "I would like to apologize to my ministers for this." 

Prayut scrapped the previous constitution when he seized power from an elected government in a 2014 coup. The current constitution was drawn up at his behest.

Critics have called on him to be accountable for the mistake and said the failure to recite the full oath of allegiance could render his Cabinet illegitimate and unable to perform its duties.