Updated

A top Kenyan official on Thursday accused the United States of trying to overthrow Kenya's government by supporting activists even as baton-wielding police used tear gas to break up an anti-government protest in downtown Nairobi.

A press statement from the National Security Advisory Committee asked the Ministry of Foreign Affairs to summon the U.S. government aid arm, USAID. The security committee said it wants to learn of USAID's alleged plans to "topple the government using activists."

The security committee said it possesses credible intelligence documents detailing how USAID has funded demonstrations by activists.

"NSAC warned that the consistent plans to destabilize the current government will not be tolerated at any costs, especially where activists are sustainably funded to tarnish the country's and leaders' reputation regionally and internationally," said the statement.

The letter was signed by Francis Kimemia, the chairman of the National Security Advisory Committee and the secretary of the president's Cabinet. Kimemia confirmed in a text message to The Associated Press that the letter is authentic.

In response, U.S. Ambassador Robert Godec said the United States is a strong and committed partner to the government of Kenya and has been for 50 years. He said accusations that the U.S. is trying to undermine or destabilize Kenya's government are false.

"The government of the United States, including the U.S. Agency for International Development (USAID), coordinates its activities in Kenya in a transparent manner and in collaboration with the government of Kenya," Godec said. "We have always and will continue to share information about our programs with the Kenyan government."

Kimemia's accusatory note is another dent in U.S.-Kenyan relations, which are strained over the Kenyan government's belief that the U.S. State Department tried to persuade Kenyan voters not to cast their ballots for Uhuru Kenyatta, who was elected president last year.

In addition, Kenyatta and his deputy president, William Ruto, blame the West for the charges the two face at the International Criminal Court for crimes against humanity related to the massive violence and killings after Kenya's 2007 election. The case against Kenyatta appears close to collapsing but Ruto's is expected to move forward.

Kenyan leaders also still fume at a $55 million U.S. program called "Yes Youth Can" that aims to increase political participation by Kenya's youth and to improve their earnings.

Boniface Mwangi is a Kenyan political activist who appears to have been mentioned in the national security committee letter, which referenced a "Boniface M." being funded by the U.S.

Mwangi led Friday's demonstration and was detained by police before he fled out of the back of the police truck. Mwangi accuses Kenyatta's government of curtailing civil liberties and of trying to gag civil society.

"There are so many things that are wrong with this country. The government is afraid of the truth. Now the truth has become terrorism," he said in an interview, where he noted Kenya has been independent from Britain for 50 years. "Fifty years is a long time for us to complain about the same thing. We firmly believe Kenyans have the power to transform their society if they do the little things within their power."

Another protest leader, Hussein Khaled, executive director Haki Focus, said Kenya has not made enough progress in those 50 years.

"We are still the same spot. Police are operating with impunity, police operating like a police state breaking the law with impunity," Khaled said, adding later: "We don't want to bequeath the same country we inherited from our parents."