NEW YORK - US President George W Bush deflected a secret Israeli request last year for bunker-busting bombs to attack Iran's main nuclear site, saying he had authorised new covert action to sabotage Iran's alleged effort to develop nuclear weapons, the New York Times reported Sunday. The covert American move, started in early 2008, was aimed at to disrupt Iran's nuclear supply chain abroad and undermine electric and computer systems and other networks on which Iran depends, the newspaper reported, citing unidentified US senior foreign officials. The covert programme aimed to delay Iran's future ability to produce weapons-grade fuel and its needs to produce a workable nuclear weapon, the newspaper reported. Iran maintains its nuclear programme is for peaceful purposes and not weapon-oriented. The US Secretary of Defence Robert Gates advised Bush that any overt attack on Iran would prove ineffective and lead to the expulsion of international inspectors, the Times reported. The Times report also said the White House was unable to determine whether Israel had decided to carry out the strike before Washington objected or whether Prime Minister Ehud Olmert was trying to get Bush to act more decisively before he leaves office this month. Israel's request was for the specialised bunker-busting bombs that it wanted for the attack that tentatively involved flying over Iraq to reach Iran's nuclear facilities at Natanz, where the country's only known uranium enrichment plant is located, the newspaper said. The White House spurned requests for the bombs and flyover but said it would improve intelligence-sharing with Israel on covert US efforts to sabotage Iran's nuclear programne. The United States did give Israel one item on its shopping list: high-powered radar, called the X-Band, to detect any Iranian missile launchings. It was the only element in the Israeli request that could be used solely for defence, not for offence, the report said. Israel, known to have the only nuclear arsenal in the Middle East, bombed the site of a suspected atomic reactor site in Syria in 2007. Details of the expanded US covert programme and the Bush administration's efforts to talk Israel out of attacking Iran emerged from 15 months of interviews with current and former US officials, international nuclear inspectors, outside experts and European and Israeli officials, the Times said. None of those interviewed would speak on the record, the paper said, adding it omitted many details of the covert efforts from its report at the request of senior US intelligence and administration officials. It said the interviews also suggested that while Mr Bush was extensively briefed on options for an overt American attack on Iran's facilities, he never instructed the Pentagon to move beyond contingency planning, even during the final year of his presidency, contrary to what some critics have suggested." But warned that financial sanctions against Iran were inadequate, Bush turned to the CIA, according to people involved in the covert programme, authorising a broader effort aimed at Iran's industrial infrastructure supporting its nuclear programs, the Times said. While the paper said details were closely held by US officials, it quoted one as saying, "it was not until the last year that they got really imaginative about what one could do to screw up the system." But the official said, "none of these are game-changers" in that the efforts would not necessarily cripple Iran's programme. Under Bush, whose term ends on January 20 when Barack Obama becomes president, the United States has sought tougher UN sanctions against Iran to halt its nuclear programme, which Western nations believe is designed for making weapons. Iran, which has no formal diplomatic relations with the United States, says its nuclear programme is for peaceful purposes, not weapon oriented. The Times said some Bush administration officials remained skeptical of the covert programme's chances of success given what one said was Iran's proximity to achieving weapons capacity. Others held that Israel would not have been dissuaded from attacking if they believed the US effort was unlikely to prove effective, the paper said. In its dealings with Israel, Washington was especially distressed by Israel's request to fly over Iraq to reach Iran's major nuclear complex at Natanz, a request the White House flatly denied, the paper reported. But the exchanges and tension prompted Washington to step up its intelligence-sharing with Israel, including the new US efforts aimed at sabotaging Iran's nuclear infrastructure. The Times said its interviews indicated Bush was convinced by officials, led by Defence Secretary Robert Gates, that an overt attack on Iran would likely be ineffective, bringing the expulsion of international inspectors and driving Iran's nuclear effort further from view. "Bush and his aides also discussed the possibility that an airstrike could ignite a broad Middle East war in which America's 140,000 troops in Iraq would inevitably become involved," the paper said. Bush instead opted for more intensive covert action, it said, adding that those operations and the issue of whether Israel would agree to anything less than a conventional attack on Iran posed vexing problems for Obama.