Noppadon Pattama insists he did nothing wrong
Thai Foreign Minister Noppadon Pattama has resigned after a top court ruled he had violated the constitution by signing a deal over a disputed temple.
Cambodia had been petitioning to have the temple on the Thai-Cambodian border listed as a World Heritage site.
But judges ruled the government should not have backed Cambodia without asking parliament, as the temple is built on land disputed by the two countries.
Some Thais saw the move as an implicit surrender of sovereignty claims.
The Preah Vihear Hindu temple, near the Thai-Cambodian border, was awarded Unesco World Heritage status on Monday.
Mr Noppadon made the announcement that he was stepping down on national television.
"But I insist that I have done nothing wrong. I have not sold out the country. I love Thailand, and would not cause any damage to the country," he said, fighting back tears.
"I want to see national reconciliation. In order for the government to continue working to solve the country's problems, I resign."
Always a controversial choice as foreign minister - he used to be a lawyer for former Prime Minister Thaksin Shinawatra, who was ousted in a military coup in 2006 - Mr Noppadon's position became untenable after backing the Unesco World Heritage bid.
His support for the temple's listing sparked a wave of nationalist anger, and matters were made worse when the Constitutional Court ruled two days ago that the minister's actions had violated the constitution.
Mr Noppodol is the second minister to resign from Thailand's embattled government, and according to the BBC's South East Asia correspondent Jonathan Head, he may well not be the last.
Another minister resigned in May over allegations he had insulted the king.
The constitutional court, one of the country's top three judicial bodies, also disqualified the health minister from office this week.
The courts have become unusually assertive in punishing government officials for what in the past might have been viewed as minor offences, our correspondent says.
The role of the judiciary was strengthened by the new constitution, which was drafted under military rule last year, so it could act as a check on the power of elected governments.
As prime minister, Mr Thaksin was often accused of abusing his power - a principal reason given to justify the coup that ousted him.
The coalition government now led by his allies risks being crippled by these repeated judicial interventions, our correspondent adds.
The 900-year-old Hindu temple has been the subject of a border dispute for decades.
The International Court of Justice ruled in 1962 that it belonged to Cambodia and has been at the centre of a bitter dispute between the two neighbours ever since.