* Israel's Iron Dome "doesn't work"-Iranian defence official
* Iranian experts "repel" cyber threat to offshore platforms
* Tehran hard-pressed by Western sanctions over nuclear work
By Yeganeh Torbati
DUBAI, Oct 8 (Reuters) - Iran derided Israel's air defences as feeble on Monday, citing a drone incursion into its arch-foe's airspace, but did not say it had sent the aircraft shot down by the Israelis at the weekend.
It also accused Israel and others of masterminding what it said was a cyber attack on communication networks on Iranian offshore oil and gas platforms in the past few weeks.
With tension high over Iran's disputed nuclear programme and Israeli threats to attack it, the remarks by Iranian officials pointed to possible aspects of a shadow war waged by the two adversaries and perhaps by Israel's Western allies, whose sanctions have battered the Iranian economy and currency.
Jamaluddin Aberoumand, deputy coordinator for Iran's Islamic Revolutionary Guard Corps, said the drone intrusion showed that Israel's Iron Dome anti-missile defence system "does not work and lacks the necessary capacity", Fars news agency reported.
The Israeli air force shot down a drone on Saturday after it crossed into southern Israel, the military said, but it remained unclear where the aircraft had come from.
Iron Dome is designed to shoot down short-range guerrilla rockets, not slow-flying planes such as drones.
The Israeli military said the drone was first spotted above the Mediterranean near the Hamas-ruled Gaza Strip to the west of Israel and shot down by a fighter plane over Israeli territory.
Israeli parliament member and former military spokesman Miri Regev described it as "Iranian drone launched by Hezbollah", the Lebanese Shi'ite group that fought a war with Israel in 2006.
Israeli defence officials have not confirmed this. Hezbollah has sent a drone into Israeli airspace at least once previously.
Aberoumand attributed claims the drone was made by Iran to a "psychological operation" by Israel, but did not confirm or deny them. "The Zionist regime (Israel) has many enemies," he added.
Israel has threatened to bomb Iran's nuclear sites if diplomatic efforts fail to stop the nuclear work it believes is aimed at getting weapons capability, a charge Tehran denies.
Iran has responded with threats to attack U.S. military bases in the region and retaliate against Israel if attacked.
Mohammad Reza Golshani, head of information technology for the Iranian Offshore Oil Company, told Iran's Mehr news agency Iranian experts had been able to repel the cyber attack on the information networks on offshore oil and gas platforms.
"This attack was planned by the regime occupying Jerusalem (Israel) and a few other countries," Golshani said. Telephone communications on the platforms were now normal.
In an unrelated blow to Iran's energy exports, the gas flow on a pipeline carrying Iranian natural gas to Turkey was halted on Monday by an explosion in eastern Turkey, where Kurdish militants have claimed repeated pipeline attacks in the past.
Iran, the world's No. 5 oil exporter, has tightened cyber security since 2010 when its uranium enrichment centrifuges were hit by the Stuxnet computer worm, which it blames on Israel or the United States. Neither has acknowledged planting the worm.
Iran has reported several computer attacks in recent months and a Revolutionary Guard commander said last month the country would defend itself in case of a "cyber war".
Tehran is seeking to developing a national Internet system, which it says would improve cyber security. But many Iranians say the plan is the latest way to control their access to the Web, which is already highly censored.
Iran's hardline clerical leaders are determined to prevent any new wave of unrest after the bloody turmoil that followed President Mahmoud Ahmadinejad's disputed re-election in 2009.
But street protests erupted last week over the plunging value of the rial, which lost a third of its dollar value in 10 days as Western sanctions on Iran's oil and banking sectors cut the country's ability to earn hard currency from oil exports.
Very little trading occurred on the open market on Monday, with the government-promoted rate of 28,500 rials to the dollar attracting little interest among those with dollars to sell.
The authorities have pressed dealers to trade dollars at certain rates and have arrested money changers accused of speculating. Others, unwilling to use state-set rates and afraid to trade at black market rates, are retaining their dollars.
Ahmadinejad and his administration are bearing the brunt of the blame for the rial's fall. Parliament voted on Sunday to consider halting further reform of Iran's food and fuel subsidies, a centrepiece of the president's economic platform.
Iran's Supreme Leader, Ayatollah Ali Khamenei, has stayed above the fray, saying only that the Islamic Republic - which has also been disconcerted by the revolt convulsing Syria, its closest Arab ally - will not bow to outside pressure.