"This relic has been respected by Buddhist followers for thousands of years," he said. "This theft cannot be accepted. The perpetrator and any associates who connived to commit such a crime must be prosecuted according to the law of Cambodia."
National Police spokesman Kirt Chantharith said the theft was discovered Tuesday when a guard was woken by a barking dog and found the lock to the shrine's door had been damaged and the urn removed.
He said police questioned 13 of the shrine's guards and detained six as suspects, but that authorities had no information about the relics' location. "We need more time to do the investigation," he said.
Ek Tha said the relics had been moved by late King Norodom Sihanouk in 2002 from Phnom Penh, the capital, to the mountain shrine in the former royal city of Udong in a ceremony attended by tens of thousands.
Several countries in Asia possess relics believed to come from the body of Buddha.