PHNOM PENH, May 11 (FN) — U.S. Ambassador to Cambodia William Heidt on Wednesday denied that the power was behind the so-called"Black Monday"protests in Cambodia, which resulted in a brief arrest of eight protesters.

The envoy made the denial during a meeting with Cambodia's Foreign Minister Prak Sokhonn, according to Chum Sounry, spokesman for the Ministry of Foreign Affairs.

"The ambassador vehemently denied that the U.S. has urged (association and non-governmental organization activists) to stage the 'Black Monday' protests,"the spokesman told reporters after the meeting.

However, the ambassador acknowledged that he had met with association and non-governmental organization representatives days before they launched the protests.

The denial came after some media outlets reported that the U.S. was behind the protests.

Cambodian anti-riot police on Monday prevented about 40 black-dressed human rights activists and land rights activists from marching to a planned protest at Prey Sar prison on the outskirts of Phnom Penh and detained eight of them, including local rights group Licadho deputy director and two foreigners— a German man and a Sweden woman who also work for Licadho.

The eight detainees were released on the same day after they signed contracts promising not to do such illegal protests again.

The group launched the protests to demand the government to release five human rights defenders, who were jailed late last month on charges of bribing a witness in a sex scandal case, but the government said that the group's movement was designed to cause chaos and unrest in the society.

Prime Minister Hun Sen said on Tuesday that the security measures the government took against those protesters were to maintain peace and political stability.