A United States general in Afghanistan has been fired after accusing President Hamid Karzai and his corruption-plagued administration of being out of touch and ungrateful for American support.

Major General Peter Fuller, deputy commander of NATO's mission to train and equip Afghan forces, was dismissed after making "inappropriate public comments", the NATO-led international force said late Friday.

Fuller's comments made public some of the frustrations expressed privately by US and other foreign military officers and diplomats about working with Karzai and his government.

In an interview published by news website Politico Thursday, Fuller said Afghan leaders did not fully recognise the human and financial cost borne by the United States in Afghanistan and were "isolated from reality".

He also directly criticised Karzai after the president said last month that Afghanistan would support Pakistan if Islamabad ever went to war with the United States.

"Why don't you just poke me in the eye with a needle?" Fuller said of Karzai's comments.

"You've got to be kidding me... I'm sorry, we just gave you $11.6 billion and now you're telling me, 'I don't really care?'"

He added: "When they are going to have a presidential election, you hope they get a guy that's more articulate in public."

US General John Allen, commander of the NATO-led International Security Assistance Force (ISAF) in Afghanistan, said the remarks did not reflect the state of the international force's relationship with Karzai's administration.

"These unfortunate comments are neither indicative of our current solid relationship with the government of Afghanistan, its leadership, or our joint commitment to prevail here in Afghanistan," Allen said in a statement.

"The Afghan people are an honorable people and comments such as these will not keep us from accomplishing our most critical and shared mission -- bringing about a stable, peaceful and prosperous Afghanistan."

US Defense Secretary Leon Panetta fully backed the decision to dismiss Fuller with immediate effect, spokesman Captain John Kirby told AFP.

A spokesman for ISAF in Kabul, Lieutenant Gregory Keeley, said it did not have any information on whether Fuller, a two-star general, would be leaving the military or redeploy to another role.

Last year, General Stanley McCrystal, then commander of international troops in Afghanistan, was dismissed by President Barack Obama over comments made by him and his aides about senior political leaders to Rolling Stone magazine.

NATO's mission to train and equip the Afghan army and police to take increasing control of security after foreign combat troops leave in 2014 is seen as one of the most important parts of the military effort in Afghanistan.

Afghan security force numbers have increased significantly in recent years, growing from around 190,000 in late 2009 to about 305,000 today. That figure is due to rise to 352,000 by November next year.

But problems persist, including poor literacy and questions over issues such as cronyism.

News of Fuller's sacking emerged as Lieutenant General Daniel Bolger Saturday took overall command of NATO's training mission in Afghanistan from Lieutenant General William Caldwell, who has completed a two-year tour of duty.

Elsewhere in the interview, Fuller used an unusual analogy to illustrate how he had to tell Afghan officials why they could not have equipment like F-16 fighter jets and tanks.

"You can teach a man how to fish, or you can give them a fish," said Fuller.

"Were giving them fish while theyre learning and they want more fish! (They say) I like swordfish, how come youre giving me cod? Guess what? Cods on the menu today."

He added that one unidentified Afghan figure had told him he only wanted tanks so he could use them in parades.