ULAN BATOR, Aug. 21 -- China and Mongolia on Thursday agreed to lift their relationship to a comprehensive strategic partnership and pledged to further strengthen their traditional friendly cooperation.

In a joint declaration signed by visiting Chinese President Xi Jinping and his Mongolian counterpart, Tsakhiagiin Elbegdorj, the two sides reiterated their commitment to developing their traditional friendship on the basis of the principles of stability, mutual benefit and mutual respect.

The two sides pledged to expand friendly cooperation in line with the spirit of the 1994 Treaty on Friendly Relations and Cooperation between China and Mongolia and other relative documents.

They emphasized that each of them will not conduct or participate in any activity, sign any treaty or join any group that will impair the other's sovereignty, security and territorial integrity.

The two sides also agreed that each of them will not allow any third party to carry out activity on its soil that is harmful for the other's sovereignty, security and territorial integrity.

China stressed that it will adhere to the principles of "amity, sincerity, mutual benefit and inclusiveness" in interaction with its neighbors, and is committed to pursuing win-win cooperation and common development.

The two sides agreed that China's approach will generate more opportunities for the development of China-Mongolia relations as well as regional cooperation.

The Mongolian side reaffirmed that the government of the People's Republic of China is the only legitimate government of China and that Mongolia firmly supports China's stances on Taiwan, Tibet and Xinjiang affairs.

The two sides will maintain the momentum of bilateral high-level interaction and enhance exchanges and cooperation between the legislatures and governments of the two countries, said the declaration.

China said it is happy to see Mongolia develop friendly cooperation with all countries and international organizations in the world and backs its efforts to improve the environment for foreign investment.

China respects and supports Mongolia's status as a nuclear weapon-free country, said the declaration, adding that the two sides are opposed to the transfer into and deposit in Mongolia of nuclear waste in any way.

According to the declaration, China and Mongolia will set up a strategic dialogue mechanism between their foreign ministries, encourage their political parties to share experiences, and initiate mutual visits in their defense sectors.

They also agreed to strengthen exchanges between their law enforcement agencies and boost cooperation in fighting terrorism as well as transnational and organized crime.

Xi arrived in Ulan Bator on Thursday morning for a two-day state visit to Mongolia. He held talks with Elbegdorj in the afternoon and is also scheduled to meet Mongolian Prime Minister Norov Altankhuyag and Chairman of the Mongolian State Great Hural Zandaakhuu Enkhbold on Friday.