Poneman also said the United States would work with partners to ensure the global oil market remains well-supplied.

“The United States is in very frequent and close contact with many members in the international community, certainly including China, our key partner in the UN Security Council,” he told reporters of consultations on the sanctions.

“So we have very robust and continued consultation with all of those partners, including China.”

His comments came a day after the US House of Representatives passed legislation on Wednesday that would expand sanctions on Iran, cracking down on a wider range of energy issues and closing some loopholes in existing energy and financial sanctions.

Some senators in both parties are also working on legislation to tighten sanctions on Iran, the world’s fifth-biggest oil exporter.

“We’ll have many consultations with US Congress and I think you’ll end up hearing the United States and the international community speaking with one voice in terms of the importance of Iran responding to these global requirements to comply with their international commitments,” Poneman said.

Asked if the United States was concerned if China, the biggest buyer of Iranian crude, kept importing while other countries cut, he declined to comment directly but said it was important the oil market was well-supplied.

“If the market remains well-supplied, then alternatives to Iranian purchases are going to be available. That is why we particularly welcome continued efforts by the existing producers. I’m pleased also to see the production coming back,” he said, referring to output resumption from Libya and Iraq.

“As long as we can work, with producers and consumers, to make sure that global market requirements and those of individual nations are met, that’s the best thing we can do in the short term.”

In the long term, it was important to change excess dependence on oil imports and diversify to other types of energy sources, such as nuclear power and renewables, he said.

Poneman was visiting Tokyo to discuss issues including nuclear cooperation with Japan following the radiation crisis at the Fukushima Daiichi power plant triggered by the March 11 earthquake and tsunami.