Tehran, March 29, IRNA � The Iranian nuclear delegation has refused to budge on key issues as deadline for deal approaches, a senior US official said.

'The Iranians are being very tough on the most difficult issues,' a senior US official told CNN on condition of anonymity.


'We are headed toward the deadline, so in some ways we expect this, but we really don't know if we will get there,' the source added.

'We spent all of yesterday pushing the Iranians,' the diplomat said. 'They are not moving. It's very difficult. It is not going well.'

Nuclear talks reached a critical point Saturday as the ministers of France and Germany arrived to strike a final deal over Tehran's nuclear program ahead of Tuesday's deadline.

Tehran and the G5+1 have been holding talks aimed at reaching an agreement on Iran's nuclear activities since November, 2013.

The sides must reach a final agreement on the issue before the start of July, 2015. The political framework for the deal should be agreed upon by the end of March.

If an agreement is reached, the sanctions that have been imposed by the West against Iran over its nuclear activities will be lifted.

The most recent round of negotiations between Iran and the G5+1 started in Lausanne on Thursday and will last until Sunday, March 29.

By IRNA