The three men were caught taking photos of each other naked in the Banteay Kdei temple at the world heritage site on Thursday.
"The temple is a worship site and their behaviour is inappropriate," Chau Sun Kerya, a spokesperson for the Apsara Authority, the government agency managing the Angkor complex, told the AFP news agency.
The three were all in their early 20s, according to passport details released by the Cambodian authorities.
The three tourists have "admitted they really made a mistake by taking nude pictures", the Apsara Authority said in a statement, adding that police are building a case against them.
They could face charges of public exposure, which is punishable by up to six months in prison and a maximum 106-euro fine and/or making pornography, which could a year in jail and a fine of up to 442 euros.
Last Saturday the Apsara Authority threatened to take legal action against those responsible for the publication of photos of an Asia woman posing topless in the Angkor Archaeological Park, dubbing them “inconsiderate and pornographic”.
The images were originally posted to the “Wanimal” photography blog, which features photos of nude or partially nude women often posing in public places, in October 2013 with the caption “Khmer Lady”, according to the Cambodia Daily website, but a storm blew up at the weekend after they were posted on several Facebook accounts.