KABUL (Reuters) - The Afghan government has hit back at remarks by the head of NATO who said Kabul must recognize the sacrifices made by other states, calling the alliance's war on terrorism inAfghanistan "aimless and unwise".

In the latest outburst of vitriol from the Afghan leadership deriding its Western allies, the spokesman for Afghan President Hamid Karzai said the people of Afghanistan "ask NATO to define the purpose and aim of the so-called war on terror".

"As they question why after a decade, this war in their country has failed to achieve its stated goals, but rather has resulted in the loss of thousands of innocent lives and destruction of their homes", Aimal Faizi said in a statement.

NATO Secretary-General Anders Fogh Rasmussen said on Monday he was concerned about the increasingly harsh rhetoric between Karzai and the United States, which contributes the largest contingent to the NATO-led International Security Assistance Force (ISAF) in Afghanistan.

He told a news conference in Brussels that "we would also expect acknowledgement from the Afghan side that we have ... invested a lot in blood and treasure in helping President Karzai's country to move forward".

More than 3,000 foreign troops from 50 countries have been killed in Afghanistan since the U.S.-led military intervention began in 2001. Some estimates put the cost to the United States alone of the Afghan war in the hundreds of billions of dollars.

Speaking to the state news agency, BIA, Faizi said: "The people of Afghanistan ask NATO Secretary-General that while it is clearly known to NATO that terrorism sanctuaries are outside Afghanistan, why this war then continues in their homes and villages unproductively?"

"Therefore, the Afghan people consider this war as aimless and unwise to continue," he said.

WAR OF WORDS

Karzai marred a debut visit to Afghanistan by the new U.S. defense secretary, Chuck Hagel, last week by accusing Washington and the Taliban of colluding to convince Afghans that foreign forces were needed beyond 2014, when NATO is set to wrap up its combat mission and most foreign troops are to withdraw.

Washington denies the accusation, and found support from Rasmussen who said the allegation was "absolutely ridiculous".

Karzai's remarks further strained already fraught ties between the president and the Western allies who are fighting to protect his government from insurgents.

The United States still has 66,000 troops in Afghanistan, down from almost 100,000 two years ago at the height of a surge ordered by President Barack Obama. Washington intends to withdraw most of them by the end of next year but wants to negotiate a continued, smaller presence.

Karzai has been increasingly assertive towards the United States. Last month, he ordered U.S. special forces to leave Wardak province after residents complained that they, and Afghans working with them, were torturing and killing civilians, an allegation denied by the Americans.

Opposition politicians saw Karzai's order as a political move to bolster his party's support base ahead of a presidential election next year. Karzai is not allowed to stand again.

"As every day passes, our relations with the international community get worse. Whenever President Karzai makes some remarks against Americans, money goes out of the country and businessmen leave," Ahmad Zia Massoud, leader of the Afghan National Front opposition alliance, told Reuters.

He said as tension had risen between Washington and Kabul in the past year, and as Afghanistan prepared to go it alone, some $4.5 billion had poured out of the country and into Dubai where worried Afghans are building homes.

(Additional reporting by Mirwais Harooni; Editing by Jon Hemming)