Around six people were arrested outside the United States Embassy in Phnom Penh yesterday for attempting to stage a small protest, but were released later in the afternoon after agreeing to not demonstrate again without a City Hall permit.

However, the motives of the demonstrators, from the little-known Ponleu Siri Aryakmetrey group, remained unclear as of press time. They were taken in by police and Daun Penh district security guards while approaching the embassy with a banner reading: “We unite together to extinguish the third world war”.

“We do not know where they were from,” said City Hall spokesman Met Measpheakdey. “We do not know whether their organisation is legitimate or not, or has registered or not.”

Measpheakdey added that the handful of demonstrators were questioned and released at 3pm. He said authorities were uncertain about the motives of the protest, but Un Sam Ath, police chief of Daun Penh district’s Wat Phnom commune, said they had come to “ask the US to have peace for Cambodia”.

Another group, the League for Peace and Youth Network, said in August it would organise anti-US protests but has not done so. The group was behind a 2015 protest at the National Assembly that ended with Bodyguard Unit members brutally beating two opposition lawmakers. Anti-US rhetoric by government officials, meanwhile, has escalated over the last two months.

A US Embassy spokesman confirmed the presence of the “peaceful demonstration” yesterday, but directed further queries to local authorities. A security guard, who requested anonymity, said the group had come once before to protest.