In talks with Saudi Crown Prince Nayef on Saturday, Wen also said his government would encourage "reputable" Chinese companies to invest in Saudi Arabia's ports, railways and infrastructure, Xinhua news agency reported. "China and Saudi Arabia are both in important stages of development, and there are broad prospects for enhancing cooperation," he told Prince Nayef, who is a senior member of the Saudi government, according to Xinhua. "Both sides must strive together to expand trade and cooperation, upstream and downstream, in crude oil and natural gas," said Wen. The Saudi kingdom is already China's biggest source of imported crude oil.