CHENGDU - Joe Biden, vice-president of the United States, on Monday morning left Chengdu, capital of southwest China's Sichuan Province, wrapping up his six-day official visit to China.

During his stay, Biden met with President Hu Jintao, top legislator Wu Bangguo and Premier Wen Jiabao in Beijing. Vice-President Xi Jinping held talks with him also in the capital and accompanied him to Sichuan.

"I think the two leaders -- Xi and Biden -- developed a strong personal relationship, " said US Ambassador to China Gary Locke while attending a a ceremony for dozens of American friendship volunteers to China later on Monday morning.

Noting that Biden's visit was "productive and successful," Locke said Biden believes personal relationships are key to improving relations and avoiding mistrust and miscalculation.

"Our two countries' economies are so interdependent," Locke said, citing Biden's remarks that the United States and China "have a stake in each other's success."

Biden arrived in Beijing last Wednesday at the invitation of Xi.