BEIJING, Sept. 12 (Xinhua) -- President Xi Jinping has called on customs workers in China to uphold fine conduct and improve supervision and services to serve the country's high-quality development and high-level opening up.

Xi, also general secretary of the Communist Party of China Central Committee and chairman of the Central Military Commission, made the remarks on Monday in a letter replying to workers of the Khunjerab Pass, the land port on the China-Pakistan border in northwest China's Xinjiang Uygur Autonomous Region.

In his letter, Xi said they have overcome difficulties such as cold temperatures and low oxygen air, and stayed committed to their duties, demonstrating the fine spirit of customs workers in the new era.

As this year marks the 20th anniversary of the implementation of the customs rank system in China, Xi extended sincere greetings to customs workers across the country.

Workers stationed at the Khunjerab Pass recently wrote to Xi, expressing their determination to contribute to advancing Chinese modernization.