The Thai secretary to an international panel set up by Myanmar to advise on the Rohingya crisis has quit his post, dealing another blow to the credibility of a body meant to demonstrate the government's commitment to resolving the issue.

Explaining his decision, Kobsak Chutikul, a retired ambassador and former member of Thailand's parliament, said the panel of foreign and local experts, which met this past week for the third time in the capital, Naypyitaw, had "been kept on a short leash" and achieved little in the six months since its formation in January.

Kobsak said he quit on July 10, but his departure has not previously been made public.