MPs have approved a motion imposing tougher economic sanctions against Iran.
The government motion - passed without a vote in the Commons on 13 December 2011 - confirmed the decision to tighten economic sanctions, including a ban on dealings with Iranian banks, extending to the country's central bank.
Financial Secretary to the Treasury Mark Hoban said the government had decided to impose the sanctions on Tehran because of "serious concern" about its nuclear weapons programme from independent inspectors.
In its latest report, the International Atomic Energy Agency (IAEA) presented new evidence suggesting that Iran was secretly working to obtain a nuclear weapon.
Iran has dismissed the claims as fictitious.
Relations between between the two countries have worsened in recent weeks, following attacks on the British embassy in Tehran - which were met with the expulsion of Iranian diplomats from the UK.
Labour former Justice Secretary Jack Straw expressed concern that "only two other countries" - the US and Canada - had supported imposing financial sanctions on Iran, questioning why the government had not sought support from other EU countries.
He said it had left the British embassy "rather isolated and an easy target for the thugs in Tehran".
Mr Hoban denied the government had been left isolated by deciding not to wait for EU countries to impose the same measures.
He told MPs that French President Nicolas Sarkozy had written to say that he supported the UK's stance, adding the issue would be debated again at the EU next month.