Human Rights Watch is urging U.S. President Barack Obama to use his upcoming visit to Cambodia to call for an end to longstanding human rights abuses, including alleged extrajudicial killings, torture, and abductions.

The New York-based rights group said in a report Tuesday over 300 people have been killed in politically motivated attacks in Cambodia in the past two decades of Prime Minister Hun Sen's rule. The group says rather than investigate the crimes, Cambodia's government has instead ignored them and in some cases even promoted those believed to be responsible.

Human Rights Watch deputy Asia director Phil Roberts tells VOA that President Obama, who next week will become the first ever U.S. head-of-state to visit Cambodia, is in a unique position to publicly demand human rights improvements.

“We're calling on President Obama to really strongly and publicly raise these human rights concerns, to press for accountability, and to insist that it can't be business as usual with the Cambodian government, given the gravity of these human rights violations.”

The report praised the U.S. for being “one of the most outspoken critics of the Cambodian government's human rights record.” But Robertson says Washington's actions have not always been consistent with its words.

“For instance, when the U.S. gave national police chief Hok Lundy an award (in 2006) for his contribution to anti-terror work. I mean, Hok Lundy was well-known throughout Cambodia as a brutal killer, someone who struck fear in the hearts of ordinary Cambodians. He was certainly no one who deserves any sort of accolade from the United States government.”

During his 27 years in power, Prime Minister Hun Sen has repeatedly promised reforms, such as creating an independent judicial system and more accountable police force. But Human Rights Watch says he has not followed through on those promises, and that foreign governments have failed to hold him accountable.

Robertson says it is time for the U.S. and other governments and donors, which he says account for up to 50 percent of the Cambodian national budget, to insist on changes.

“The president should … make it quite clear to Hun Sen that the U.S. is not fooled, that the U.S. is not having the wool pulled over its eyes, that it understands in a very clear way the human rights challenges that exist in Cambodia and that it is prepared to comment on those.”

Cambodian officials have suggested that Prime Minister Hun Sen will hold bilateral talks with Mr. Obama when the U.S. leader travels to Phnom Penh for the ASEAN and East Asia summits beginning next Monday.