TEHRAN: A fire broke out Wednesday at an Iranian shipyard in the southwestern port of Bushehr, damaging several vessels under construction without causing any casualties, local media reported.

"An extensive fire has engulfed Delvar Kashti Bushehr boat factory," with thick smoke covering the area south of Bushehr city, state television IRIB reported. Five to seven vessels were damaged by the blaze, the cause of which was unknown, Bushehr government official Jahangir Dehghani was quoted as saying by the semi-official ISNA news agency.

Video footage on IRIB's website showed a fire truck and several men dousing smouldering vessels which appeared to be fishing boats. Iran's only nuclear power plant is located about 20 kilometres (12 miles) from Bushehr.

The incident is the latest in a string of fires and explosions at military and civilian sites across Iran in recent weeks.

Two explosions rocked the capital Tehran in late June, one near a military site and the other in a health centre, the latter killing 19 people. Fires or blasts also hit a factory south of the city last week, leaving two people dead, and the Natanz nuclear complex, about 250 kilometres south of Tehran. Iranian authorities called the Natanz fire an "accident" without elaborating and later said they would not reveal the cause, citing "security reasons".

The string of fires and explosions have prompted speculation in Iran that they may be the result of sabotage by arch enemy Israeli. The Jewish state accuses the Islamic Republic of seeking to acquire a nuclear bomb while Tehran insists its nuclear programme is entirely peaceful.