BANGKOK — The government on Tuesday said it will invite a group of foreign diplomats for a talk, after they accompanied the leader of Future Forward Party when he reported to a police station to hear a sedition charge last week.

Foreign affairs minister Don Pramudwinai said the diplomats’ actions amount to “interfering” with Thailand’s justice system. He said foreign dignitaries are only allowed to observe legal proceedings involving their nationals, not Thais.

“This kind of incident has never happened in other countries, and it cannot happen [here],” Don told reporters at Government House. “The Ministry of Foreign Affairs will invite them for a discussion to ask for their cooperation and reach a mutual understanding to not let it happen again, because it’s against diplomatic principles.”

Read: Gov’t Says Trying Thanathorn in Military Court is Fair

Diplomats from 10 countries and two international organizations were present when Future Forward Party chairman Thanathorn Juangroongruangkit reported to police on April 6 to hear a sedition charge filed against him.

Police accuse Thanathorn, whose party placed third in last month’s election, of assisting a group of anti-junta demonstrators to escape police custody back in 2015. He was charged under Section 116 of the Criminal Code, which carries a maximum penalty of 10 years. Government officials have confirmed Thanathorn will stand trial in a military court.

Future Forward spokeswoman Pannika Wanich said the diplomats showed up to observe the police’s questioning of Thanathorn on their own volition.

“If they didn’t think it was important, they wouldn’t have been there,” Pannika told the media.

Although foreign diplomats – mostly from Western nations – have routinely observed police inquiries and court trials of prominent activists since the 2014 coup, Don said today they cannot do so.

“It’s Thai justice procedures,” the minister said. “If they have any questions or don’t understand something, they should make inquiries to the Ministry of Foreign Affairs about whether they can observe the proceedings.”

Thanathorn said he will submit his defense testimony to the police on May 15. His court appearance has yet to be appointed.