Iranian police shot dead two gunmen among a group of attackers who tried to rescue two convicted bank robbers from imminent execution in a southeastern Iranian town, a news agency reported today.

About 25 people were wounded in a shoot-out after the assailants opened fire on security forces preparing for the execution in Sirjan town, the semi-official Fars News Agency reported, citing a senior official in Kerman province.

Police returned fire and the execution of the convicts was later carried out, it said, reporting about the culmination of a series of events after family members of the two robbers earlier foiled the first attempt to put them to death.

On Tuesday, state radio said relatives started hurling stones during the execution and in the ensuing confusion "stole the bodies" of the men, who later turned out to still be alive.

The authorities tracked them down in a nearby village, Fars said, adding that five of their accomplices were also detained.

It was when the execution was due to resume later in the day that the shooting occurred. Iranian executions usually take place by hanging inside prisons, but are occasionally also carried out in public.

"Some people attacked security forces guarding the place of execution (before the arrival of the convicted robbers) ... police forces retaliated and in this clash two of the attackers were killed," Fars said.

Southeastern Iran is the scene of frequent clashes between heavily-armed drug smugglers and security forces.

Murder, adultery, rape, armed robbery, apostasy and drug trafficking are all punishable by death under Iran's sharia law, practised since the 1979 Islamic revolution.

Amnesty International listed Iran as the world's second most prolific executioner in 2008 after China, and says it put to death at least 346 people last year.