U.S. Ambassador to Cambodia William Heidt, rear center, gives a press conference at the U.S. Embassy in Phnom Penh, Cambodia, Tuesday, Sept. 12, 2017. Associated Press/Heng Sinith PHNOM PENH (Reuters) - The United States embassy in Cambodia said on Wednesday it had stopped issuing some types of visas to Cambodians because Cambodia is not taking back citizens the United States wants to deport.

The new policy comes at a time that US President Donald Trump's administration is trying to crack down on immigrants who are in the United States illegally.

The US embassy in Phnom Penh said the visa restrictions were applied in accordance with US Secretary of Homeland Security rules applying to a country that refuses to accept or is unreasonably delaying the return of its nationals.

"The Secretary of State must order consular officers to suspend issuing visas until informed by the Secretary of Homeland Security that the country in question has accepted the individuals," an announcement from the embassy said.

The embassy had discontinued issuing some visas for Cambodian foreign ministry employees above the rank of director general and their families, with limited exceptions, it said.

The argument over the return of Cambodians deported from the United States is only one of many between the United States and Cambodia, which has accused detained opposition leader Kem Sokha of plotting treason with US support.

Earlier this year, Cambodia stopped accepting the deportation of Cambodian nationals who had been convicted of crimes in the United States, saying it wanted to renegotiate a settlement agreement on human rights grounds.

Reacting to the visa announcement, government spokesman Phay Siphan said it showed the United States did not recognize human rights.

"Cambodia still cooperates with the US," he said. "But while the US tells the world that it respects human rights, in reality they don't. They just drop bombs to kill people."

(Reporting by Prak Chan Thul; Editing by Matthew Tostevin)