China and central Asian countries are planning to apply for adding historical sites along the 2,000-year-old Silk Road to UNESCO's world cultural heritage list in 2011, an official in central China's Henan Province said Thursday.

"The final application will be submitted to UNESCO in two years," said Guo Hongchang, mayor of Luoyang City in Henan.

The 7,000-kilometer-long Silk Road was mainly a trade route linking Asia and Europe. It extended from the Chinese cities of Luoyang and Xi'an, to Europe via south and central Asian countries.

Along this road, gunpowder, papermaking and printing technologies reached the West, while Western mathematics and medicine came to China.

"A multinational application will be a better choice if we want to present the whole historical culture of the ancient Silk Road," said Jing Feng, an official with the UNESCO World Heritage Center's Asia-Pacific Region Program.

In 2006, more than 50 experts and heritage officials from UNESCO and China, Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan reached an agreement for a multinational application for Silk Road in UNESCO World Cultural Heritage List.

The blueprint called for measures to protect cultural relics, improve the environment at sites and carry out promotional campaigns along the route.

"The application will help us to exchange the experience of cultural heritage protection with other historical sites," said Guo Yinqiang, head of Luoyang's Cultural Heritage Bureau.

From the end of 2005, Luoyang began a protection plan for its relics site of Sui and Tang Dynasties (581-907) where the Silk Road started at that time. It has already invested more than 80 million yuan (about 11.7 million U.S. dollars) in the project.

Last year, the Luoyang government moved six enterprises, including a cement factory and a bearing factory, out of its relics of Sui and Tang dynasties, to improve the environment.