Border trade between North Korea and China, halted by Pyongyang Monday after the death of its leader Kim Jong Il, has begun to pick up, Chinese officials said. The resumption of trade began along the China-North Korea Friendship Bridge connecting China\'s border city of Dandong with the North\'s Sinuiju city, China\'s official Xinhua news agency reported, quoting local customs officials. The report said iron sand -- sand containing heavy concentrations of iron -- a major North Korean export to China, was among the items coming through the border. Major Chinese exports to the isolated, communist country include food, daily necessities and building materials.Trade between the two countries was expected to return to normal next week, officials said. Many North Koreans in Dandong used the route to return home to mourn the death of their leader, but others expressed their condolence while staying back in the Chinese city, the report said. China has been a close ally of North Korea. Chinese President Hu Jintao, who visited the North Korean embassy in Beijing to express his condolence, said it is the \"persistent policy\" of his government and the Communist Party of China to continuously consolidate and develop the traditionally friendly relations with North Korea, Xinhua said. The Chinese leader expressed confidence that North Koreans would closely unite around their Worker\'s Party and turn their grief into strength under the leadership of Kim\'s son and successor, Kim Jong Un, to achieve peace and stability on the Korean Peninsula.