More than 40% of Britain's Afghan military equipment may not return to the UK, according to Government exit strategy plans.
Millions of pounds worth of resources are expected to be scrapped, sold or given away following the withdrawal of troops under proposals drawn up by the Ministry of Defence (MoD).
The plans - which are still to be finalised - have raised fears high-tech material could end up in the hands of the Taliban.
Government estimates suggest about 11,000 containers worth of equipment are currently in theatre, including around 3,000 vehicles.
Of these, military chiefs plan to bring back some 6,500 loads, at a cost of tens of millions of pounds.
It would leave around 4,500 containers (40.9% of kit) to be disposed of in Afghanistan, according to plans revealed to the Press Association under the Freedom of Information Act.
The MoD has not disclosed the quantity or value of equipment it intends to hand to the Afghan state.
It said decisions would be made "on a case-by-case basis" as experts questioned the reliability of the Afghan National Security Forces (ANSF) and warned kit could be passed to the enemy.
Dr John Louth, of the Royal United Services Institute (RUSI) defence think tank, said leaving 40% of equipment was not unusual following an overseas conflict but suggested there was a "risk to leaving things behind".
"What is benevolent today could be quite nasty tomorrow," he said.
"If people have equipment that they wish to sell, they will sell it.
"It is naive to think that won't occur, particularly given the nature of society and communities in that part of the world. It is a life of trade and absolutely everything is tradable."
He added: "The typical danger is that people who aren't your friend could somehow end up with it and use it.
"There could also be technical issues. Quite often we don't know everything that is in our kit.
"There could be some very interesting technology that, if you thought about it, you wouldn't want a third party to get."
Security strategist David Livingstone, an associate fellow at foreign affairs think tank Chatham House, urged the Government to set out a clear policy to account for the equipment in theatre.
"The MoD has to be honest about what will happen," he said.
"The public will care very much about the losses in Afghanistan. It is the MoD's duty to the taxpayer to explain what is going to happen to all of this stuff."
He added: "There will always be a risk that something with a UK Army serial number will get passed across."
Shadow defence secretary Jim Murphy said the Government should "not waste a moment" in negotiating cost-effective transit routes to bring equipment back to Britain.
"In an uncertain world it is essential that the UK retains much of the equipment deployed in Afghanistan," he said.
"The Government should be open about UK equipment that will be scrapped, sold or wasted.
"The UK's military needs must be the priority but during transition we must consider how we can best support Afghan forces who have a long-term challenge to secure lasting peace."
The drawdown of British troops has been at the centre of high-level discussions between Prime Minister David Cameron and Afghan president Hamid Karzai this week.
The talks came after president Karzai admitted the government would not survive without western military and financial aid following the end of the Nato mission.
While United Nations troops must withdraw from Afghanistan by the end of next year, president Karzai conceded that stability in the country would take longer as the Afghan police and army continue to struggle against the Taliban.
The MoD said it was reviewing its policies to ensure any equipment handed over was done so in line with Parliamentary, Treasury and National Audit Office rules.
"We are conscious that unco-ordinated gifting of equipment could jeopardise the sustainability of the ANSF," it said.
"Before gifting any equipment we must determine that the ANSF can sustain this equipment in terms of cost of ownership, support and enduring training.
"Our approach on gifting will, therefore, be co-ordinated with that of Nato and ISAF (the International Security Assistance Force) in order to ensure that our Afghan partner forces receive the equipment they need without duplication or unnecessary complexity."
The MoD said "considerable analysis" was in progress to determine how much material would move, following the consumption, selling, scrapping and gifting of material in theatre.
It plans to transport low-grade material back to the UK over ground at a cost of between £5,000 and £12,000 per container, according to the plans.
Vehicles and sensitive material would be flown back to Britain at a cost of up to £30,000 per load.
The Government is considering various possible withdrawal routes which include transporting goods through either Pakistan or the Central Asian Republics.
Agreements have already been confirmed with Kazakhstan and Uzbekistan. Flight and surface transit negotiations are in progress with Tajikistan and Kyrgyzstan.
An MoD spokesman said: "The MoD continues to assess what equipment will be redeployed from Afghanistan to ensure a proper balance is achieved between military resources and the tasks we are committed to undertaking.
"Decisions on what to do with equipment will be made on a case-by-case basis using the principles of operational priority and value for money to the UK taxpayer."
The MoD said later: "The redeployment of equipment and assets from Afghanistan is a huge and complex task and while no decisions have yet been made, it is nonsense to suggest that state-of-the-art, high-tech assets will be allowed to fall into the hands of the Taliban.
"The Defence Secretary has already said that in the majority of cases recuperating and refurbishing equipment bought for Afghanistan will be the best value-for-money option.
"When bringing equipment back to the UK does not represent value for money for the taxpayer, it will be either sold or gifted to Afghan National Security Forces - although obviously we would not be helping the Afghan forces by giving them equipment they are unable to maintain."
Speaking during a visit to UK forces at Camp Bastion, Defence Secretary Philip Hammond said it was possible that all recoverable kit could be out by the end of next year when combat operations are due to end.
He told BFBS, British Forces News: "Because we have been able to close bases faster than we imagined would be possible even six months ago, because of the progress than the ANSF has made, it is possible that we will have all the kit out by the end of 2014 but I don't want to make promises yet.
"We are still in the process of planning and organising the withdrawal of our equipment and we need to look at all the equipment that's here and take it back to the UK if it makes good sense and it is value for money for the British taxpayer to take it back, refurbish it and put it back into our core equipment stock.
"If it is not value for money then we won't do it and we have a range of options, including the possibility of gifting appropriate equipment if that's the best and most sensible thing to do."
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