Ashton: Sanctions should encourage Iran 'to negotiate'

European Union foreign ministers have formally adopted an oil embargo against Iran over its nuclear programme.

The sanctions involve an immediate ban on all new oil contracts with Iran, while existing contracts will be honoured until 1 July.

Tehran denies that it is trying to develop nuclear weapons and says talks and not sanctions are the only way to resolve the dispute.

EU foreign policy chief Catherine Ashton said the aim of the sanctions was to "make sure that Iran takes seriously our request to come to the table".