“We are complying with the sanctions. They do recognize previous commitments and contracts,” Voser said in an interview with Reuters at the annual IHS CERA energy conference in Houston, adding that the old contracts will be fulfilled and shipments delivered “within a matter of weeks.

Voser had previously said that the company will abide by the sanctions put in place by the Washington and Europe, aimed at curtailing sales of Iran’s oil as means of pressuring Tehran to end its nuclear program.

Industry sources have said Shell had been shipping around 100,000 barrels per day (bpd) of Iranian crude into Europe, plus a similar quantity into Japan under a deal with its joint venture, Showa Shell, that expires in March. 

Shell also purchased a cargo of Iranian crude that was delivered to a Singapore refinery this week, according to Reuters data and trade sources, raising questions among traders about whether it would continue to lift the country’s oil until it became illegal.

In both Washington and Europe, sanctions are coming into effect to crimp Iran’s ability to sell its oil exports to choke off funding for its nuclear program. Washington and Brussels believe Tehran is trying to develop nuclear weapons, a charge Iran denies. 

A European Union oil ban against Iran is slated to begin on July 1. The US, which doesn’t import crude from Iran, has imposed sanctions on countries that transact with Iran’s oil exporters, making it harder to deal with Iran in dollars or euros, and threatening penalties for countries that do so without waivers. 

In response, some of Iran’s biggest Asian buyers have cut imports of crude from the Islamic Republic, the world’s fifth larges oil exporter and the second biggest producer in OPEC after Saudi Arabia. India, China and Japan buy almost half of Iran’s estimated 2.6 million barrels per day of oil exports.

Carlos Pascual, the State Department’s special envoy for international energy issues, said US sanctions are taking hold faster than expected.

“In effect, a process many thought would be phased in over time has actually taken hold pretty quickly,” Pascual said during a presentation at the CERA conference, adding that top oil exporters such as Saudi Arabia, the UAE and Kuwait were sensitive about the importance of maintaining oil market stability. 

Tensions around the standoff between the West and Tehran have gripped oil markets this year, sending prices of Brent crude oil to over $124 a barrel.