Iran and six world powers have extended into next week their talks on finding a comprehensive agreement of Tehran's nuclear programme, Digital Spy reports.

The deadline for reaching an agreement was 30 June, but all parties agreed to extend it by another week, to 7 July.

Russian Foreign Minister Sergei Lavrov said on Tuesday that a deal was now "within reach".

But U.S. President Barack Obama has said he will still "walk away from the negotiations if... it's a bad deal".

And Iran's President Hassan Rouhani warned: "If the other side breaches the deal, we will go back to the old path, stronger than what they can imagine."

The so-called P5+1, which includes the US, UK, France, China and Russia plus Germany, want Iran to scale back its sensitive nuclear activities to ensure that it cannot build a nuclear weapon.

Iran, which wants international sanctions that have crippled its economy lifted in exchange, has always insisted that its nuclear work is peaceful.