- Vienna talks miss the most recent deadline of 9 July
- Stalemate includes mechanism for removal of sanctions
Iran and the six world powers attempting to reach an agreement on Tehrans nuclear programme continued negotiations into the night of 11 July after missing several deadlines.
The previous deadlines 30 June, 7 July and 9 July have already been missed and there remains difficult issues to resolve, according to US Secretary of State John Kerry.
Kerry, Irans Foreign Minister Mohammad Zarif and EU foreign policy chief Federica Mogherini met for almost 90 minutes of talks on 11 July and met again later in the evening between two meets of the P5+1 world powers the US, France, Germany, the UK, China and Russia.
Sticking points in the talks include the mechanism for lifting UN, US and EU sanctions against Iran.
Tehran has also insisted in recent days that a deal should include the lifting of a UN arms embargo.
Iran and the P5+1 group of world powers are aiming to reach a deal to give Tehran relief from sanctions in exchange for limiting the development of its nuclear programme.
If a deal is reached, the removal of sanctions is expected to bring significant benefits to the Iranian economy, with the immediate gains including an increase in oil production and exports, and a payout of more than $100bn in frozen overseas oil funds.