THE exhibition on historical relics of the Han and Tang Dynasties will be on display at the Hong Kong Museum of Art until Saturday. Entitled ''Treasures of Chang'An - Capital of the Silk Road'', the impressive exhibition features more than 100 masterpieces selected from seven major museums in China's Shaanxi province, including porcelain wares, pottery wares and figures, bronze, goldand silver wares, stone sculptures and silk fabrics. It provides a comprehensive view of the technical and artistic achievements of the Han and Tang periods and a vivid illustration of the extent of early western cultural influence in China. There are examples of the finest and the most fascinating art objects from the national treasures of China. Some of them are grade one cultural relics that are rarely shown outside the country. Visitors will also see the tri-colour ''sancai'' glaze pottery wares and figurines considered to be the most outstanding and representative art forms of the Tang Dynasty. Jointly presented by the Urban Council, the Cultural Bureau of Shaanxi province and the Hong Kong Culture and Art Foundation, the exhibition is on display at the Special Exhibition Gallery of the Museum of Art. To give visitors a better understanding of the exhibits, the museum will provide a new audio guide service during the exhibition period. Audio guide sets, each equipped with a portable cassette player and a pre-recorded tape on the historical background and artistic merits of the exhibits, will be available for loan and use inside the museum. Admission is $10 or $5 for students or senior citizens. The museum, located next to the Space Museum in Tsim Sha Tsui, opens from Fridays to Wednesdays.