Police in Cambodia have detained 11 activists who were trying to hand over a petition to foreign embassies urging them to help free two dozen anti-government protesters detained during a crackdown this month.

Chan Saveth, an official from local human rights group Adhoc, says the activists were trying to deliver the petitions to four embassies, including the U.S. and France.

Police could not be reached for comment and it was not immediately clear what laws the activists were accused of breaking Tuesday.

The activists are advocating for the release of 23 people arrested in early January in connection with protests against the government.

The protests are the biggest challenge in years to the authoritarian rule of Prime Minister Hun Sen, who has led the country for almost three decades.