Four Iranian convicts were executed on Monday in Zahedan, the capital of the south-eastern Sistan-Baluchistan province, official news agency IRNA reported.
One of the four was part of the gang that kidnapped a Belgian couple in August 2007 in Sistan-Baluchistan. The gang had demanded the release from prison of the brother of its leader, Ismael Shahbakhsh, in exchange for the Belgians.
The Iranian authorities rejected the demand and arrested one of the kidnappers, dpa reported.
Bandit gangs in the Sistan-Baluchistan province, which borders Afghanistan and Pakistan, are usually involved in drug trafficking and use kidnappings as a means of trying to force the release of their members from prison.
Two more convicted kidnappers and a murderer were also hanged in Zahedan. Their death sentences had been confirmed by the Supreme Court, IRNA said.
Murder, rape, sabotage and the trafficking of drugs in quantities in excess of five kilograms are crimes punishable by death in Iran.