A US attack on Iran is "unlikely" because the American military is bogged down in Iraq and Afghanistan, said an Iranian official Sunday, following renewed US accusations that the Islamic republic is funneling weapons to Iraqi militias. Last week both Adm. Mike Mullen, chairman of the US Joint Chiefs of Staff, and Defense Secretary Robert Gates accused Iran of stepping up its military support for Iraqi militias and said that all military options to deal with the situation were on the table. "We see it unlikely that they plan to enter a new disaster which they themselves believe will have unpleasant consequences for the region and the world," said Foreign Ministry spokesman Mohammad Ali Hosseini. Hosseini also mocked the accusations of increased military support, saying "if someone adds up the US claims about hauling weapons to Iraq by Iran, it will be a huge and unbelievable amount." Mullen said Friday that the military is preparing to roll out evidence, including date stamps on newly found weapons caches, to prove that recently made Iranian weapons are flowing into Iraq at a steadily increasing rate. Iran and the US have had no diplomatic ties since 1979 US embassy take over in Teheran. Since last May they have held three rounds of ambassador-level talks on security in Iraq.