The European Union has imposed severe new sanctions on Iran due to its refusal to suspend its nuclear activities.

Sanctions include a ban on all new contracts to import Iranian oil to EU member states and the freezing of assets of Iran’s central bank in the EU.

In a joint statement, David Cameron, Angela Merkel and Nicholas Sarkozy supported the sanctions and called on Iran to abide by international obligations.

“[…] The Iranian leadership has failed to restore international confidence in the exclusively peaceful nature of its nuclear programme. We will not accept Iran acquiring a nuclear weapon.

"Iran has so far had no regard for its international obligations and is already exporting and threatening violence around its region.

“We call on Iran’s leadership immediately to suspend its sensitive nuclear activities and abide fully by its international obligations. The door is open to Iran to engage in serious and meaningful negotiations about its nuclear programme.

"Until Iran comes to the table, we will be united behind strong measures to undermine the regime’s ability to fund its nuclear programme, and to demonstrate the cost of a path that threatens the peace and security of us all.”

Iran responded to the increased pressure by threatening to close the Strait of Hormuz, a vital trade route for global oil supplies.

"If any disruption happens regarding the sale of Iranian oil, the Strait of Hormuz will definitely be closed," said Mohammad Kossari, deputy head of the Iranian parliament's foreign affairs and national security committee.

The US responded to Tehran’s threat by pledging to keep the Strait open.

"The Strait of Hormuz needs to remain open and we need to maintain this as an international passageway," Ivo Dalder, US Ambassador to NATO told the BBC.

"We will do what needs to be done to ensure that is the case."