UK warns Iran over nuclear plans
The British government says Iran's threat to restart part of its nuclear programme - uranium conversion - is "unnecessary and damaging".
The UK Foreign Office (FCO) urged Iran not to take unilateral steps that could jeopardise talks with three European Union nations - known as the E3.
The remarks came after a top Iranian official set a Sunday deadline for the EU to propose economic incentives.
The UK - the current EU president - said these would be given in a week.
This was in accordance with the decisions of the Geneva meeting in May between Iran and the three European countries - Britain, France and Germany - as well as the EU's foreign policy chief Javier Solana, said the FCO spokesman.
This is threatening to become a dangerous escalation, says the BBC's Jon Leyne.
The US believes Iran is trying to build a nuclear bomb, but Iran insists its programme is for civilian use only.
Iran suspended all uranium conversion and enrichment activities in November 2004 as a result of international pressure.
However, it has always insisted that the suspension was temporary and that it would resume some of its nuclear activities regardless of EU proposals.
The European states have threatened to refer Iran to the UN Security Council for possible sanctions if Iran resumes its nuclear activities.