The four were among 10 foreigners who stripped naked and took photos on Mount Kinabalu on May 30. A local official has said the foreigners' behavior was disrespectful to the mountain, which is believed to be sacred, and caused an earthquake last Friday that killed 18 climbers.
Dutch citizen Dylan Snel, British student Eleanor Hawkins and Canadian siblings Lindsey Petersen and Danielle Peterson pleaded guilty in a court in Sabah state on Borneo island, The Star newspaper said on its website.
The Star said the women were topless while the two men were totally nude.
The Malay Mail online news portal said the court was told the group of 10 had challenged each other to see who could remain naked the longest in the cold.
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They ignored a plea by their mountain guide not to strip, it said.
It quoted defense lawyer Ronny Cham as saying the four were young people whose generation was accorded more freedom and liberties. He said they had suffered enough trauma and that extensive international news coverage of the incident has served as deterrent for others.
Lawyers and police could not immediately be reached for comment.
The magnitude-5.9 earthquake sent rocks and boulders raining down on trekking routes on the 4,095-meter (13,453-foot) mountain. The victims were nine Singaporeans, six Malaysians, a Filipino, a Chinese and a Japanese.
The quake damaged roads and buildings and also broke one of the famous twin rock formations on the mountain known as the "Donkey's Ears."
Sabah Deputy Chief Minister Joseph Pairin Kitingan blamed the tragedy on the foreigners for having shown disrespect to the mountain, believed by local tribes to be a resting place for the dead. He said a special ritual will be conducted to appease the mountain spirits.