Iran has taken the unusual step of denying claims that it conducted DDoS and other cyber-attacks against US banks connected to the enforcement of US economic sanctions on the county. According to reports that emerged in the US last week, since late 2011 Iran has been conducting a campaign against a range of US companies, including disrupting the websites of the Bank of America Corp, JPMorgan Chase & Co and Citigroup."Iran has not hacked the US banks," Gholam Reza Jalali, the country's Iran's Civil Defence Organisation told the Iranian state Fars News Agency on hearing the reports.Although the officials quoted by Reuters were unsourced, Senator Joseph Lieberman -also Chairman of the Homeland Security & Governmental Affairs Committee - went on the record about the source of the attacks in his mind."I think this was done by Iran and the Quds Force, which has its own developing cyber-attack capability," he reportedly said.""I believe it was a response to the increasingly strong economic sanctions that the United States and our European allies have put on Iranian financial institutions," he said.Going to the length to deny such claims is relatively unusual for Iran although it remains possible that attacks could have been carried out unofficially through private organisations based in the country.Separately, Iran has started blocking Gmail and Google which some fear could be a sign that the country's declared intention to set up its own 'domestic Internet' might be about to be put in operation.The explanation is the state's desire to block the 'anti-Islamic' propaganda film hosted on YouTube that has caused huge controversy in recent weeks, but others see this as a pretext. Facebook and YouTube are widely used channels of political dissent.