Iran is open to holding further talks with six world powers over its nuclear programme, President Mahmoud Ahmadinejad said on Sunday, a day after the failure of the latest round of dialogue.

A new onshore gas field worth $50 billion has been discovered in the southern part of Iran, oil minister Masoud Mirkazemi has said.

Foreign diplomats were set to kick-off on Saturday a two-day tour of Iran's atomic sites at the invitation of Tehran, in a bid to drum up support for its contentious nuclear programme.

Iran has hanged five men convicted of drug trafficking, the state broadcaster website reported on Thursday, taking to 33 the number of executions in the Islamic republic in 2011.

Atomic chief and acting foreign minister Ali Akbar Salehi declared in a report Saturday that Iran can make its own nuclear fuel plates and rods, technology the West had said Tehran did not possess.

A 5.1-magnitude earthquake struck southern Iran's fars province on Saturday injuring 11 people and damaging some villages, the state television said on its website.

Iran said on Tuesday it has invited ambassadors of some of the six world powers and European Union nations to visit its nuclear facilities ahead of talks in Istanbul over its atomic programme.

Iran hanged on Tuesday a man found guilty of giving information on Iranian missiles to Israeli intelligence service Mossad, state news agency IRNA reported, quoting the Tehran prosecutor's office.

Iran is yet to agree on an exact date for the next round of nuclear talks with world powers due to be held next month in Istanbul, foreign ministry spokesman Ramin Mehmanparast said Tuesday.

"There is an agreement on the venue of the meeting but the date has not been finalised yet. consultations are ongoing to organise talks in Istanbul somewhere around the end of January," Mehmanparast told reporters.