Six world powers and Iran began talks in Vienna on Tuesday in pursuit of a final settlement on Tehran's disputed nuclear programme in the coming months despite warnings from both sides that a deal may prove impossible.

Expected to last two or three days, the meeting is the first since the powers - the US, Russia, China, France, Britain and Germany - struck an interim accord with Iran in November under which Iran scaled back its most sensitive nuclear work in return for some sanctions relief.

In a final deal, Western governments want to define the permissible scope of an Iranian nuclear programme and resolve their concerns that Tehran is seeking the capability to build an atomic bomb.

Iran, which denies having any such goal, wants the complete removal of painful economic sanctions imposed by Washington, European governments and the UN. - Reuters