The leaders of Afghanistan and China on Wednesday signed agreements on trade and economic cooperation, and vowed to work harder to combat terrorism in Central Asia.

Visiting Afghan President Hamid Karzai and China''s Hu Jintao pledged to step up cooperation in maintaining security in the region, while presiding over the signing of a series of economic and trade agreements.

China "will always support and aid Afghanistan in its peaceful reconstruction and support Afghanistan''s efforts to establish sovereignty, independence and territorial integrity," China Central Television quoted Hu as saying.

"Both sides should ... actively strike at terrorism, separatism and religious extremism and organised cross-border crimes in an effort to maintain regional peace and stability."

Hu called for deeper political ties and more visits between leaders, while urging economic cooperation in mining, agriculture, hydro-electric and irrigation and infrastructure projects, the report said.