BEIJING - A Chinese man convicted of stealing art pieces from the heavily-guarded Forbidden City in Beijing appealed his sentence on Monday, demanding a 10-year reduction to his jail term, according to the court handling the case.

Shi Baikui, 27, was sentenced to 13 years in jail by the Beijing No 2 Intermediate People's Court on March 19. He broke into the Palace Museum, more popularly known as Forbidden City, last May and stole nine pieces of art works made of gold and jewels -- all on loan from Hong Kong and insured for a total of 410,000 yuan ($65,000).

Huang Shiyong, Shi's lawyer, said he had submitted the appeal to the court, requesting the court to reconsider the sentence.

"There is no legal provision saying that stealing from the Forbidden City is a crime more severe than other theft," Huang said, adding that he hoped the court would reconsider, maybe to reduce the jail term to three years which would be in line with other theft convictions.

Shi was apprehended by police at an Internet cafe in Beijing's Fengtai district 58 hours after the theft.

Six pieces were recovered and the three missing were estimated to be worth 150,000 yuan ($23,800) in total.

The court earlier said Shi's punishment had been meted out with leniency because he had confessed to the thefts in a candid and cooperative manner and repented for his wrongdoing.

Shi said during trial that the theft was a "spur-of-the-moment" act.

The incident sparked public concern over security loopholes in the Forbidden City, former home of Chinese emperors, in the heart of Beijing.

The museum said in a statement after Shi's sentence was announced that it will draw lessons from the case and work to improve the museum's security as well as its staff's awareness of responsibility.

The museum also called for intensified efforts to crack down on cultural relic theft and robbery cases, as similar crimes have become a problem in China in recent years.

The museum's newly appointed curator, Shan Jixiang, said the management had long been aware that its alarm system was outdated and a four-year upgrade began in November 2009. By last December, about 60 percent of the work had been completed.

In a recent interview with Xinhua, Shan said the museum must employ "the world's most advanced security equipment and technology."