TEHRAN (AFP) - Iran on Tuesday launched naval manoeuvres in the Gulf, and announced plans for another exercise in the strategic Strait of Hormuz later this week, media reports said.Revolutionary Guards naval units began a four-day exercise inside Iranian waters at South Pars, a joint gas field between Iran and Qatar, a Guards spokesman was quoted as saying by the Fars news agency.The drill, dubbed “Fajr 91,” is aimed at honing “capabilities in executing defensive and security scenarios,” Admiral Alireza Nasseri said without elaborating.The Guards are tasked with defending Iran’s territorial waters in the Gulf. The regular navy, meanwhile, on December 28 begins an exercise dubbed “Velayat 91,” covering an area that includes the Strait of Hormuz, the Sea of Oman and parts of the Indian Ocean, navy chief Admiral Habibollah Sayari said in remarks reported by the ISNA news agency.Warships, submarines and missile defence systems will be used and tested during the exercise, Sayari said. “We will definitely respect the maritime border of our neighbours, and conduct the manoeuvres based on international law,” Sayari said.“Iran aims to demonstrate its defensive naval capabilities by conducting this exercise, and send a message of peace and friendship to regional countries.”Iran frequently conducts missile tests and manoeuvres to underline its military muscle and has repeatedly threatened to close the Strait of Hormuz to oil tanker traffic should it be attacked.The strait is a narrow channel at the entrance of the Gulf through which a third of the world’s traded oil passes.The United States has warned Iran that any attempt to close the strait would be viewed as a “red line” - grounds for US military action.Iran’s navy, with 17,000 servicemen, is tasked with defending Iranian interests in the Indian Ocean and beyond. Its offshore forces are limited to half a dozen small frigates and destroyers, and three Russian Kilo class submarines.Iran regularly denounces the regional presence of foreign forces, including the US, particularly those stationed in the Gulf. It says the security of the region must be ensured “by regional countries.”Arab monarchies on the opposite side of the Gulf from Iran are worried by what they see as territorial ambitions by the Islamic republic, which frequently stresses Persia’s historic dominance over the waterway.Iran on Tuesday repelled a fresh cyber attack on its industrial units in a southern province, a local civil defence official said, accusing “enemies” of nonstop attacks against its infrastructure.“A virus had penetrated some manufacturing industries in Hormuzgan province, but its progress was halted with ... the cooperation of skilled hackers,” Ali Akbar Akhavan said, quoted by the ISNA news agency.Akhavan said the malware was “Stuxnet-like” but did not elaborate and that the attack had occurred over the “past few months.”Stuxnet, tailored specifically to target Iran’s uranium enrichment operation, struck Iran in 2010 and reportedly dealt a serious blow to its disputed atomic programme.Akhavan said one of the targets of the latest foiled attack was the Bandar Abbas Tavanir Co, which oversees electricity production and distribution in Hormuzgan and adjacent provinces.He also accused “enemies” of constantly seeking to disrupt operations at Iran’s industrial units through cyber attacks, without specifying how much damage had been caused.The Islamic state has blamed the US and Israel for cyber attacks in the past. In April, it said a voracious virus attack had hit computers running key parts of its oil sector and succeeded in wiping data off official servers.