The sanctions were a way of intensifying "peaceful, legitimate pressure on a regime which has serious questions to answer about its nuclear program, questions that it doesn't answer adequately at the moment," Hague said in an interview with the PBS News Hour.

"We don't want to see military conflict in Iran, nor do we want to see nuclear proliferation. So what we have to try is the offer of negotiation, but at the same time intensify the pressure," he went on.

At a joint news conference with the U.S. Secretary of State Hillary Clinton in Washington, Hague added that more companies will be put on the existing blacklist, mostly those operating in the financial sector, as well as energy and transport firms.

The fresh round of sanctions is due by late January.

The British top diplomat added that the international community is set to continue putting pressure on Iran to make the Islamic republic drop its controversial nuclear program.

The West, led by the United States, suspects Iran of pursuing a secret nuclear weapons program, but the Islamic Republic insists it needs nuclear power only for civilian purposes. Iran is already the subject of a wide range of international sanctions.

On December 1 foreign ministers of the European Union blacklisted an additional 179 Iranian officials and institutions linked to the government over Tehran's controversial nuclear program.