In the clearest signal yet of efforts to seek reconciliation with the Taliban, Gates told a security conference in Singapore that the gains on the Afghan battlefield were laying the ground for talks with the insurgents.

"If we can sustain those successes, if we can further expand the security bubble, (if) we have enough evidence that the Taliban are under pressure that their capabilities are being degraded, then perhaps this winter the possibility of some kind of political talks or reconciliation might be substantive enough to offer some hope of progress," he said at the annual Shangri-La Dialogue on security in the Asia Pacific region.

Gates's comments follow reports that the US has begun a secret engagement with the Taliban as it begins to withdraw troops from Afghanistan in July as part of a process to hand over all combat operations to Afghan security forces by 2014.

Officials in several countries have said there have been contacts, although these do not yet constitute a peace process.

The death of Osama bin Laden in Pakistan last month, who was sheltered by the Taliban earlier, is seen as helping the reconciliation process with the insurgents who are focused on ridding their homeland of foreign forces rather than a global agenda of jihad that bin Laden's al Qaeda has pursued.

Violence is at its highest in Afghanistan in years with the Taliban carrying out a wave of attacks across the country including the relatively peaceful regions of the north and west, despite coming under pressure from a surge of US troops in their southern bastions.

Gates said the Taliban had been ejected out from their strongholds in Afghanistan's southern provinces of Kandahar and Helmand, and the more pressure they face, the better the prospects of a political settlement.

But he warned also that while the United States supported reconciliation with insurgents, any final settlement must take into account the concerns of Afghanistan's neighbors.