Talks on Iran’s nuclear programme will continue for several more days past Tuesday, according to EU foreign policy chief Federica Mogherini.

"This does not mean we are extending our deadline. I told you one week ago more or less, we are interpreting in a flexible way our deadline, which means that we are taking the time, the days we still need, to finalise the agreement," AFP quoted Mogherini as saying to reporters during a break in the talks in Vienna.

Iran and the P5+1 world powers -- the United States, Britain, China, Russia, France and Germany have initially planned to have a deal in place by 30 June.

Last week both sides effectively gave themselves until 7 July to finalise a deal that will require Iran to dismantle parts of its nuclear infrastructure in exchange for easing economic sanctions against Tehran.

According to international newswires, a few stumbling blocks remain, including the level of access that Iran will grant to the International Atomic Energy Agency to monitor the country’s nuclear programme.

Meanwhile, Russian Foreign Minister Sergei Lavrov has said that the only major issue that remains to be solved is the arms embargo against Iran.

"There is an understanding that the major part of sanctions will be lifted," Lavrov had told reporters in Vienna as he left the talks for an economic summit at home, Lavrov said, according to Russia’s sputniknews.com.

Fewer than 10 issues that need to be "polished" to reach an agreement at the talks, Lavrov added.