HONG KONG — The author of “Crazy Rich Asians,” the best-selling novel on which the new hit film is based, never fulfilled his national service obligations in Singapore and could face a fine or potential prison term, the country’s Ministry of Defense said Wednesday.

The status of the author, Kevin Kwan, was revealed by the authorities one day after the film, which was largely set and filmed in Singapore, made its premiere there. Mr. Kwan did not attend the opening there, although the director, Jon M. Chu, and several of the film’s stars did.

Mr. Kwan, 44, left Singapore when he was 11 and moved to Houston. Singapore requires all male citizens to perform two years of service in the military, the police or the civil defense force, generally starting at age 18. Singaporeans are not allowed to renounce their citizenship until they turn 21, and can face legal problems if they try to do so without fulfilling their national service.

Some profiles of Mr. Kwan said he became an American citizen at age 18. But Singapore appears to have not given up its claims to him. The Ministry of Defense said Mr. Kwan’s application to renounce his citizenship in 1994 was rejected, as was a subsequent appeal.