Iran has hanged 13 members of a Sunni Muslim armed group known as Jundallah, or Soldiers of God, after they were convicted of carrying out a number of bombings and other attacks in the south of the country.

The executions were carried out on Tuesday in a prison in the city of Zahedan, the capital of Sistan-Baluchestan province, rather than in a public park as had originally been planned, state media said.

"This morning the executions of some members of the Jundallah terrorist group ... were carried out in prison," Ebrahim Hamidi, the provincial judiciary chief, told the semi-official Fars news agency.

There was no immediate comment on why the authorities had not staged the hangings in public.

The execution of a fourteenth suspected member of the group, Abdolhamid Rigi, a brother of its leader Abdolmalek Rigi, was postponed for a few days on the request of an intelligence official seeking "necessary information" from him for a related case, Hamidi said.

Mosque bombing

Zahedan was the scene of a bombing at a Shia Muslim mosque in May that killed at least 25 people.

Authorities blamed Jundallah, which says it is fighting for the rights of minority Sunnis in the Islamic Republic, for the attack and quickly arrested a number of suspects. 

The reports of Tuesday's execution did not mention the mosque bombing, but the official IRNA news agency said that the men were convicted as "mohareb", or one who is waging war against God, for crimes including murder, kidnappings and attacks on police.

Three people were hanged on May 30 for involvement in the mosque blast.

Sistan-Baluchestan, which shares borders with Afghanistan and Pakistan, has seen clashes between security forces and heavily armed drug smugglers, as well as suspected armed rebel groups.

Iranian authorities have said that Jundallah has close ties to "foreign forces" operating in Afghanistan, a possible reference to al-Qaeda.

The Amnesty International human rights group listed Iran as the world's second most prolific executioner in 2008, after China, and said at least 346 people were executed last year.

Iran says it implements Islamic law and rejects Western allegations of human rights violations.