Iran maintains that the purposes of its nuclear programme are peaceful
The European Union has approved new sanctions against Iran in protest at its nuclear programme.
The measures target loans to companies trading with Iran and allow for tougher cargo inspections.
Iran rejects claims that it is seeking nuclear weapons, and recently condemned the new sanctions as illegal.
Major powers agreed on Wednesday to consider further separate UN sanctions after Tehran failed to meet a deadline to freeze its nuclear activities.
The EU sanctions are seen as a strong implementation of the most recent of three UN resolutions imposing curbs Iran after it defied successive Security Council ultimatums to freeze uranium enrichment.
The measures call on member states to exercise "restraint" in committing state-funded financial support for trade with Iran, including the granting of export credits.
They also allow EU countries to inspect planes and ships travelling to and from Iran to check they are not carrying contraband goods.
Earlier this week Iran missed a deadline to reply to an offer of incentives to end its uranium enrichment programme.
France, the US and UK are pushing for new sanctions, but Russia says there is potential for more dialogue.
The fact Iran is enriching uranium has led Western powers to fear it is seeking to develop an atomic bomb.
Tehran denies there is any intention beyond peaceful energy production.