China’s premier on Friday warned Iran not to block access to the Strait of Hormuz and said his country “adamantly opposes Iran developing and possessing nuclear weapons.”

The words came as tensions are rising across the Persian Gulf and were unusually blunt for a Chinese leader. Wen Jiabao’s criticism of Tehran’s threats were well received by his Arab Gulf hosts however who fear Iran’s aspirations to regional leadership.

Wen was in the Middle East for a six day visit of Qatar, Saudi Arabia and the United Arab Emirates, three Sunni monarchies that are wary of Shia Iran projecting influence across the Gulf.

The Islamic republic is under increasing international pressure because Western nations suspect it intends to develop a nuclear weapons capability. China is among few countries that is recognized as a nuclear power under nonproliferation accords. Iran is a signatory to these treaties. A nuclear weapons program would be in violation of them.

The European Union and Japan announced this month that they would join the United States in a boycott of Iranian oil sales. The country is heavily dependent on oil revenue but its export market is limited. If Europe and Japan were to suspend their petroleum imports, it would cut Iran’s sales by roughly a quarter.

China is another major buyer of Iranian oil but its largest supplier is Saudi Arabia. The kingdom and its emirate allies have offered to expand production to make up for gaps if oil consumers won’t trade with Iran. Wen insisted that China considers its business ties with Iran independently of its diplomatic relations. He has little choice but not to. China imports more than a third of its oil and Chinese oil consumption grows by 7.5 percent per year. It needs to buy wherever it can.

The crisis in the Gulf coincides with mounting turmoil in the Sudan. Before South Sudan seceded last year, the country exported the bulk of its oil to China. The Sudanese oilfields are largely situated in the South but the export industry is controlled by Khartoum. It recently confiscated Southern crude exports as compensation for unpaid transit fees.

Although the civil war in Sudan formally ended with Southern independence there continue to be clashes along the border. Oil revenue is a source of considerable discord between the two governments. If there is a disturbance in Sudanese exports, it would force China to increase its dependence on Middle Eastern oil producers, including Iran. Chinese petroleum imports from Iran already surged by 30 percent last year.