The US government has urged Iran to study a package of incentives aimed at limiting its nuclear ambitions before formally responding.

After talks in Vienna yesterday, an agreement was reached on a package of incentives aimed at persuading Iran to halt uranium enrichment.

White House spokesman, Tony Snow, said European officials will give Iranian officials a detailed presentation in the next couple of days and that a formal response was hoped for within a matter of weeks.

But a senior Iranian nuclear official has signalled Tehran's determination to press on with its nuclear work.

Mohammad Saeedi, deputy head of Iran's Atomic Energy Organisation, said Iran planned to continue its enrichment work 'for peaceful purposes'.

Decision-making in Iran is complicated by a complex political structure with ultimate power resting in the hands of Supreme Leader Ayatollah Ali Khamenei. US officials have indicated they would wait for a formal communication from Tehran before responding.

British Foreign Secretary Margaret Beckett claimed the package gave Iran a chance to 'reach a negotiated agreement based on co-operation'.

Iran has continually insisted it wants to enrich uranium only to the level required for use in atomic power reactors and has no interest in making highly-enriched uranium.

Russia, a key arms supplier to Iran, and China, a major consumer of Iranian oil, have been most opposed to threatening Iran with sanctions if it defies demands to stop nuclear work.

US intelligence chief warns over Iran arms 

The US Director of National Intelligence, John Negroponte, has claimed that Iran could have nuclear weapons within the next ten years.

In an interview this morning, Mr Negroponte said it was his assessment that Iran was actively trying to make weapons.