Iran nuclear programme agreement ends 12-year standoff

World powers and Iran have reached a landmark deal to curb Islamic Republic's nuclear programme in exchange for sanctions relief after an 18-day marathon negotiations in Vienna.

The accord was announced on Tuesday by Iranian Foreign Minister Mohammad Javad Zarif and the European Union's policy chief Federica Mogherini in a joint statement in the Austrian capital.

The accord seeks to end nearly 12 years of nuclear standoff between Iran and the so-called P+5 nations - the US, Britain, China, France, Germany and Russia.

The accord will keep Iran from producing enough material for a nuclear weapon for at least 10 years and impose new provisions for inspections of Iranian facilities, including military sites.

Iran was resisting the probe in the country's alleged work on nuclear weapons and demanding that a United Nations arms embargo to be lifted.

It also demanded that any UN Security Council resolution approving the broader deal no longer describe Iran's nuclear activities as illegal.

Major powers accused Islamic Republic of seeking to build nuclear weapons, an aim it denied, under the guise of a civilian programme.