Prime Minister Prayut Chan-o-cha said on Friday he has ordered a probe into Amnesty International Thailand to determine if the human rights watchdog is operating in compliance with Thai law.
The move came after representatives of royalist groups on Thursday submitted a letter to the prime minister through the complaints centre at Government House in Bangkok seeking to expel the group from the country.
Gen Prayut said the Royal Thai Police (RTP) and the Interior Ministry will investigate to see if the organisation has violated the law, in which case it will be banned.
He admitted the government is under pressure to act and insisted he does not want anyone or any group to speak ill about the country.
The campaign to expel the human rights group gathered steam following its criticism of the Constitutional Court's ruling on the actions of anti-government protesters Anon Nampa, Panupong Jadnok and Panusaya Sithijirawattanakul.
The court ruled that their actions at a rally at Thammasat University in August last year constituted an attempt to overthrow the constitutional monarchy.
In the letter, the representatives of royalist groups asked Gen Prayut to probe whether the non-governmental organisation had undermined national security as well as the monarchy, and requested a look into its finances, with the goal of driving it from the kingdom.
Amnesty International Thailand has been vocal about the government's suppression of activists seeking reform of the monarchy.
Prime Minister Office's vice minister Seksakol Atthawong has also launched a campaign asking people to sign up to expel Amnesty International. The campaign aims to draw 1 million names.
Gen Prayut said the government is seeking to make sure that NGOs act in a transparent way. A draft law has been submitted to parliament for deliberation.
Under the bill, these associations will be required to clarify their sources of funds and submit an annual report with auditing details.
Foreign Affairs Minister Don Pramudwinai said yesterday there are good and bad NGOs, but declined to comment when asked about Thailand's stance on these associations.
He said he hoped the NGOs operating in Thailand have a proper understanding of Thai people and acknowledge the cultural and other differences between nations.
When asked if Amnesty International Thailand had been invited for talks, Mr Don said he had worked with NGOs for 34 years and understood their standards and practices.
Meanwhile, Amnesty International Thailand issued a statement yesterday to clarify its stance in the wake of mounting pressure.
The group said it was a non-profit organisation that has been campaigning for human rights and a just and fair society for more than six decades.