BRUSSELS (Reuters) - A programme for handing over security responsibility in Afghanistan to Afghan forces will be announced in March, with a view to launching the actual process later in the first half of this year, Nato said on Monday. The district-by-district, province-by-province transition envisages Afghan forces having full security responsibility countrywide by 2014, and should allow for a gradual reduction of the 150,000 foreign troops in the country. Nato said in 2009 that it aimed to transfer such responsibility in 10-to-15 districts and areas in 2010, but the launch has been delayed by widening insurgent violence and difficulties building up the Afghan security forces. Nato has since been vague about a start date, despite growing weariness in Western countries with the 10-year war. Nato Secretary-General Anders Fogh Rasmussen said last month he hoped the process would be launched this month - or in March at the latest. Rasmussen told a Brussels news conference on Monday the March date would be for announcing which provinces and districts would be first to make the transition - not the actual start of the process. After that, a more practical implementation process will start. Its premature to say anything about when the physical transition will take place, but it will be in the first half of 2011, as I see it today, he said. After the political decision has been taken, there is a practical implementation, but I would expect it to be relatively short. Rasmussen said he was optimistic due to what he called rapid growth in the size and quality of the Afghan security forces. He said Afghan soldiers were now taking part in most security operations and made up about half those involved. Meanwhile, a senior Nato official said on Monday that as many as 900 Afghan fighters have agreed to lay down their arms, but it is too soon to say if a drive to bring in low-level fighters can be decisive in curbing bloodshed. Major General Philip Jones, who leads Nato support of the Afghan governments efforts to broker peace with various militant factions, said reintegration of local fighters had begun in earnest three or four months ago. The pace of people coming into the programme has picked up ... but the initial steps are the first in a very long process of trying to build peace, Jones told reporters in Kabul. Its a tough and complicated and very human process at all levels, but of course it would be after 20 years of war and 10 years of insurgency. Yet many thousands more full- or part-time fighters from the Taliban and other militant groups will need to halt their hostilities if Afghanistan is to emerge from bloodshed. Violence reached its highest level last year in nearly a decade of fighting after the Taliban government was overthrown, as US President Barack Obama sent some 30,000 extra soldiers to take on Taliban militants dug in across southern Afghanistan.