WASHINGTON (AFP) - The new US commander in Afghanistan has concluded that success in the country will require a dramatic expansion of the Kabul governments security forces beyond current planned targets, The Washington Post reported on Friday. General Stanley McChrystal, who took over command of US and NATO forces last month, is already pushing for a much larger Afghan security force even before he submits a 60-day assessment of the war effort, the Post wrote on its website, citing unnamed officials. During discussions this week, McChrystal informed US Defence Secretary Robert Gates of his support for more Afghan forces, a step that would require thousands more US military trainers and billions of additional dollars, the paper said. Without major increases, we will lose the war, one US official involved in training told the Post. The Defence Department declined to confirm the report but a US Marine general leading a major offensive in southern Afghanistan told reporters on Wednesday that more Afghan security forces were urgently needed to back up American troops on the ground. Pentagon press secretary Geoff Morrell said that he could not divulge details of conversations between McChrystal and Gates on the issue. Im not going to discuss their private communications but General McChrystal still has a number of weeks yet before he is due to report back to the secretary with his assessment of the situation in Afghanistan, including whether or not the Afghan national security forces (ANSF) need to be expanded and if so, at what rate, Morrell told AFP. When he does report back, the secretary will discuss his recommendations with his advisers and if changes need to be made to the size of the ANSF, he will not hesitate to take those to the president, he said. US officers have previously said that a more substantial expansion of Afghan security forces was considered before being scaled back to current expectations. The war strategy unveiled by President Barack Obama in March calls for increasing the Afghan national army from about 90,000 to 134,000 troops, while keeping the countrys police force at about 82,000. The US defence secretary has focused on reaching the target of 134,000 for the Afghan army, Morrell said. Weve still got a long ways to go before we get to that point, he said. The secretarys attitude about this has been lets get to 134, or at least get a heck of a lot closer to 134, before we make pronouncements about going bigger than that, faster than that. Expanding the Afghan security force would involve securing more trainers, as well as international support to finance the added cost, he said. Unlike Iraq, the cash-strapped Kabul government lacks the resources to bankroll a large military and police force, said Morrell. It requires trainers, money to fund these operations and long-term it requires an international commitment to sustain a force of that size, he said. But he said if McChrystal proposes an expansion, Gates would strongly consider the idea.