Chinese President Xi Jinping and Iranian President Hassan Rouhani at a meeting at Saadabad Palace in Tehran, Iran on January 23, 2016.

China has become the latest country to say it will ignore the United States and continue to conduct business with Iran.

U.S. sanctions against Iran came into effect Tuesday and President Donald Trump has warned that countries who trade with Tehran will not be able to do business with the U.S. Trump also said he will expand the punitive measures in the coming weeks to include tougher ones related to oil production.

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China has a growing relationship with Iran's energy industry and, according to a Reuters report Wednesday, has stated it will defend those business interests.

"China's commercial cooperation with Iran is open and transparent, reasonable and fair, not violating any United Nations Security Council resolutions," a government statement said, adding that "China's lawful rights should be protected."

According to Reuters data, China buys around $15 billion worth of crude oil from Iran each year and is Tehran's top energy customer. Chinese state companies CNPC and Sinopec have also invested billions of dollars to develop oil fields in Iran.

Earlier Wednesday, Turkish Energy Minister Fatih Donmez said his country would continue to buy gas from Iran.