U.S. forces will stop taking a lead role in combat operations in Afghanistan next year but continue to support Afghan combat missions under a plan announced by Defense Secretary Leon Panetta that worried Afghans and surprised allies.

Panetta told reporters late on Wednesday the United States would remain combat-ready as it winds down its longest war but would largely shift to a train-and-assist role as Afghan forces take over responsibility for security ahead of a 2014 deadline for full Afghan control.

Our goal is to complete all of that transition in 2013 and then hopefully by mid- to the latter part of 2013 we'll be able to make a transition from a combat role to a training, advise-and-assist role, Panetta said.

Panetta's remarks ahead of a meeting of NATO defence ministers on Thursday, were interpreted by some critics and friends as meaning U.S. Forces would no longer engage in combat operations after 2013 or withdraw its forces early, but a U.S. defense official said that was wrong.

Between now and the end of 2014, we're prepared to engage in combat, whether we're in the lead or the Afghans are, he said.

The United States led the Western invasion of Afghanistan in 2001 and provides about 90,000 of the 130,000 foreign troops there and a European NATO diplomat said it was the first time Panetta he had gone on record with U.S. plans.

It is for the U.S. to decide, but he has not said explicitly that the U.S. will end its combat role in 2013. There will be a shift, but he hasn't said when the shift will end.

NATO officials stressed that while the timelines had not been explicitly spelt out before, a transition to Afghan lead would always have had to have taken place by mid-2013 to meet an end-2014 timeline as the handover process takes 12-18 months.

U.S. CIA Director David Petraeus told a congressional hearing that Panetta's comments had been overanalysed.

What Secretary Panetta was discussing was ... progressive transition. And if you are going to have it completed totally by the end of 2014, obviously somewhere in 2013 you have had to initiate that in all of the different locations, he said.

Earlier in Kabul, a senior Afghan security official said his government had not been informed of Panetta's announcement and said it throws out the whole transition plan.

Transition has been planned against a timetable and this makes us rush all our preparations, he said. If the Americans withdraw from combat, it will certainly have an effect on our readiness and training, and on equipping the police force.

Panetta discussed transition plans with NATO defence ministers, including German Defence Minister Thomas de Maiziere, who said he had followed the debate of the last few hours with surprise.

De Maiziere and NATO Secretary-General Anders Fogh Rasmussen later said there was no change in the NATO plan and British Defence Minister Philip Hammond said allies were all actually in the same place.

We all recognize that in 2013 there will be an evolution in the mission, Hammond said. The Afghans will be having lead responsibility for security throughout the whole country, but we will remain there in a combat support role and we will continue to do so in our case until the end of 2014, he said.

Panetta's comments came after French President Nicolas Sarkozy, facing a tough re-election campaign, said last month that French combat operations would end by the end of 2013, an announcement that came after four French troops were killed by a rogue Afghan soldier.

Former U.S. NATO Ambassador Kurt Volker said Panetta had erred in putting an emphasis on the 2013 date, which would make withdrawal sound more imminent and affect the situation on the ground in Afghanistan.

It's a mistake to try to accomplish something against a deadline, especially when it's such a daunting challenge. Everyone just plans around it, Volker said. (The Taliban) say 'okay, if the Afghan security forces are really in charge as of 2013, all the better'.

The concerns were heightened given Panetta's comments came just after British media published excerpts of a classified U.S. report saying that the Taliban, backed by Pakistan, remained confident of regaining control in Afghanistan despite a decade of NATO efforts.

Rasmussen said the alliance expected responsibility for security to be handed over to the Afghan security forces throughout the country by mid-2013 and for them to have full control at the end of 2014.

It is of course of crucial importance that this change of role takes place in a coordinated manner, he added, emphasising that the changes of role would have to take into account the actual security situation on the ground.

CLASSIFIED REPORT

A spokeman for British Prime Minister David Cameron reiterated his plans to end Britain's combat role by the end of 2014, leaving some troops behind to train Afghan forces.

A U.S. defence official said the process Panetta outlined envisioned continued combat operations by coalition forces in support of the Afghans as needed.

The idea ... is to transition lead responsibility for combat operations to the Afghan National Security Forces, but ISAF forces would still be expected to conduct combat operations alongside our Afghan partners, the official said.

Norwegian Defense Minister Espen Barth Eide said he was not alarmed, adding: We should all now prepare for a decent transition.

Panetta said Washington had not made any decisions on troop levels for 2013 but Washington did aim to withdraw most of its combat forces by the end of 2014.

Scaling back U.S. combat operations could give President Barack Obama an election-year lift by enabling him to point to progress in Afghanistan.

But Panetta's remarks have already drawn criticism from Obama's chief rival for the presidency and Republican lawmakers in Congress. They also prompted concern among Afghans who fear a return to Taliban rule and hope that reconciliation between all parties would deliver a better alternative.

Kabul Hotel waiter Yama, 19, expressed alarm at the prospect of an early end to a U.S. combat role. Everything Afghanistan has built during the past years would be destroyed, robbed and sold to neighboring countries, he said.

The United States has been trying to draw the Taliban into reconciliation talks with the Afghan government. But a key part of its strategy has been to increase military pressure on the Taliban to persuade it to join peace talks.

(Additional reporting by David Brunnstrom in Brussels and Rob Taylor in Kabul)