Taipei  - An improvement in Taiwan's ties with China has resulted in the island considering sending its ancient Chinese treasures on exhibit in China, but Taiwan is first seeking assurances that the artworks would be returned.

The concern surrounding their return is so high that Taiwan, which holds the bulk of the imperial art collection of China after spiriting most of it to the island at the end of the Chinese Civil War, is demanding China sign a promise called the Law of Guaranteed Return to send the items back to Taiwan at the end of the exhibition.

"Our top principle is the safe return of the artifacts," Premier Liu Chao-shiuan said this month. "China must sign the Law of Guaranteed Return before we can send the treasures on exhibition in China."

Chou Kung-hsin, director of Taipei's National Palace Museum, flew to Beijing Saturday to discuss cultural exchanges with Beijing's Palace Museum.

She said she would ask for the loan of 29 artifacts from the Beijing institution for display at an exhibition from October to January in Taipei of artworks from the era of Emperor Yongzheng (1678-1735) of the Qing Dynasty.

The show was expected to kick-start the holding of joint exhibitions by the two palace museums after China has been eager to hold talks on exhibiting the Taipei artifacts in China.

Ahead of Chou's departure, Taiwan's highest China policymaker, the Mainland Affairs Council, declared Friday that China must sign the Law of Guaranteed Return with Taiwan on a government-to-government level, not just between the palace museums.

"China has always stated that the treasures in the National Palace Museum in Taipei were stolen from China by the Chinese Nationalists, so we demand that China's parliament, the National People's Congress, sign the Law of Guaranteed Return," council spokesman Liu Teh-shun said.

"China must promise the artifacts will not be impounded and that China does not claim ownership over these artifacts," he said.

When the Chinese Nationalist government lost the Chinese Civil War to the Communists in 1949, it took the best artifacts - totalling 650,000 pieces - from the Palace Museum in Beijing and a museum in Nanjing and brought them to Taipei.

Since then, these artifacts have been preserved and displayed at the National Palace Museum on the outskirts of Taipei, which has become one of Taipei's premier tourist attractions. In 2008, 2.2 million people visited the institution.

Since 1949, it has sent some of its artworks abroad a few times, but only after their host countries signed the Law of Guaranteed Return.

Taiwan has reason to fear the seizure of the artifacts while they are on overseas exhibition because only 23 countries recognize Taiwan while more than 170 countries recognize China, which considers Taiwan a breakaway Chinese province.

Despite a thaw in tensions across the Taiwan Strait since China-friendly Taiwan President Ma Ying-jeou took office in May, China still considers the artifacts at the National Palace Museum as treasures that were looted from China.

China is seeking Taiwan's unification with the mainland, but it has not demanded the return of the museum's treasures.

Liu Guoshen, a researcher from the Taiwan Research Academy at China's Xiamen University, dismissed fears that Taiwan's artifacts might be confiscated by China.

"It is impossible for Beijing to confiscate the exhibits," he said. "History is the past. The two sides have good relations now. Interaction across the Taiwan Strait is very good. Personally, I don't think there is any problem for these artifacts to be exhibited in China."

At this stage, it was still not clear whether China, or Beijing's Palace Museum, would be willing to sign the Law of Guaranteed Return.

Even if Beijing allows an unofficial agency of the Palace Museum to sign the pact, its legality is questionable.

"The legal effect of a contract signed by two persons or legal entities shall not supersede that of the laws, particularly those concerning the execution of public authority," said Lee Shih-lo, a Taipei legal expert.

"Since China does not recognize Taiwan's sovereignty, even if Beijing signs the Law of Guaranteed Return, there is no guarantee that Beijing will return the treasures to Taipei after their exhibition in China," he said. "If Taiwan knows the risks involved, it should not send the treasures to China now as the cross-strait relationship is still unstable." (dpa)