Russian President Vladimir Putin said on Tuesday that Iran had a right to a peaceful nuclear programme but slammed as "unacceptable" its threats against its regional nemesis Israel.

"Iran is in a very difficult region," Putin told a televised question-and-answer session in Moscow.

"And when we hear threats from Iran against its neighbours, particularly Israel, when we hear from Iran that Israel must be destroyed -- I think this is completely unacceptable."

Putin appeared to be referring to comments made over the years by Iran's outgoing President Mahmoud Ahmadinejad, who will stand down when his second terms expires shortly after Friday's national election.

Russia is a close trading partner with Iran and supplies the Islamic Republic with weapons and has built its first nuclear reactor near the Gulf city of Bushehr.

But Moscow in recent years has taken a more stern line with Tehran that includes a demand for it to cooperate with United Nations nuclear inspectors.

Western powers and Israel suspect that Iran's nuclear programme is aimed at eventually developing an atomic weapon that could be used against its enemies.

Tehran counters that it needs the programme for nuclear energy and for medical research needs.

Putin said on Tuesday that Iran should not be "discriminated" against with demands for it to abandon its nuclear programme.