* NATO discusses size of post-2014 force in Afghanistan
* No decisions made, Obama weighing U.S. plans
* Afghan troops gradually assuming security role (Adds quotes)
By Adrian Croft and Phil Stewart
BRUSSELS, Feb 22 (Reuters) - NATO Allies are discussing keeping a training force of between 8,000 and 12,000 troops in Afghanistan after most foreign soldiers leave in 2014, the United States said on Friday.
NATO-led forces are gradually handing over responsibility for security to their Afghan counterparts as the bulk of foreign combat forces prepare to withdraw by the end of next year.
"A range of 8-12,000 troops was discussed as the possible size of the overall NATO mission," Pentagon spokesman George Little said after a NATO defence ministers' meeting in Brussels.
U.S. President Barack Obama has not decided how many American troops would remain in Afghanistan after 2014, he said, adding: "The president is still reviewing options."
German Defence Minister Thomas de Maiziere said earlier that U.S. Defense Secretary Leon Panetta had told allies in Brussels that the United States alone could keep 8,000 to 12,000 troops.
After Panetta denied this, de Maiziere issued a statement correcting himself and saying the number referred to the possible overall size of the post-2014 NATO mission, also expected to include European allies and some non-NATO nations.
Troop numbers are politically sensitive as voters in many allied countries are weary of the 12-year war with the Taliban.
Previous discussions at the White House focused on a range of options of between 3,000 and 9,000 U.S. troops, with military commanders most comfortable with the higher-end figures.
A senior NATO officer said last month the United States expects other NATO allies to contribute between a third and a half of the number of troops that Washington provides.
Apart from the NATO training mission, the United States will also lead a counter-terrorism mission in Afghanistan after 2014, targeting al Qaeda.
NATO allies agreed in Brussels the trainers will be stationed in the capital Kabul and in four regional headquarters, where they can advise Afghan military commanders.
"Today we asked NATO to begin planning for a range of options on the post-2014 posture that would provide for an effective regional presence not only in Kabul but at fixed sites in the north, south, the east and the west," Panetta told a news conference in Brussels.
The NATO talks about the residual force in Afghanistan came just over a week after Obama announced the withdrawal of roughly half of the 66,000 U.S. forces by early next year.
Panetta confirmed the bulk of the U.S. forces in Afghanistan would remain through the summer, allowing more than 60,000 of them to assist Afghans through peak fighting months.
U.S. troop levels would fall to about 50,000 by November this year. Panetta said the United States would keep some 34,000 troops in the country through the April 2014 Afghan presidential election to assist with security.
"Once those elections were completed, we would then begin the final drawdown of our forces towards the end of 2014," he said.
NATO is strongly considering keeping Afghan forces, largely funded by the United States and its allies, at their peak strength of 352,000 until at least 2018, as opposed to cutting them by about a third after 2015. This would cost an extra $2 billion over the three years, a NATO source said.
A larger Afghan force would give the United States greater flexibility as it withdraws its troops, said Panetta, but he added Obama had yet to make a decision on the matter. (Additional reporting by Justyna Pawlak; Editing by Jason Webb)