KABUL - Afghanistan's insurgent Taliban marked the eighth anniversary of the U.S. invasion Wednesday saying they have no "agenda" to harm other countries but would continue fighting as long as America and its allies remain in the troubled nation.

The Taliban insistence that it would pose no threat to other countries appeared aimed at countering suspicions that the Islamist movement would support al Qaeda's global jihad if they returned to power. Supporters of the war fear that al Qaeda would regain its once-dominant position in Afghanistan if the Taliban topple the U.S.-backed Afghan government.

In an Internet statement Wednesday obtained by the SITE Institute, a U.S. group that monitors terror messages, the Taliban said their goal was "independence and establishment of an Islamic system."

"We did not have any agenda to harm other countries including Europe, nor we have such agenda today," the group said. "Still, if you want to turn the country of the proud and pious Afghans into a colony, then know that we have an unwavering determination and have braced for a prolonged war."

The statement came on the anniversary of the U.S. invasion that ousted the Taliban for harbouring al Qaeda leader Osama bin Laden. U.S. forces first launched airstrikes into Afghanistan on Oct. 7, 2001, less than a month after al Qaeda carried out the Sept. 11 attacks in Washington and New York.

U.S. troops, with help from Northern Alliance militia members from Afghanistan's north, quickly pushed the Taliban out of Kabul and their southern stronghold in Kandahar, leading some U.S. officials to declare the Afghan fight a quick and easy victory.

But that original military success has turned into an increasingly violent counterinsurgency fight in recent years.

An unprecedented number of U.S. troops -- about 65,000 -- are in Afghanistan today, along with 40,000 more forces from other NATO countries.

The Taliban called on foreign forces to leave, an unlikely event despite heated debate in the U.S. over how to quell the conflict.

"We call on the American rulers and their allies of the coalition once again to put an end to the game of occupying Afghanistan and killing the Afghans under unsubstantiated pretexts," the statement said.

"At the beginning, they were promising they will withdraw within three months, in their words, after eliminating the so-called terrorism," the statement said, referring to U.S. forces. "Contrarily, today, eight years (later) ... they have built up hundreds of military bases in Afghanistan and Iraq."

"We believed from day one that this is not a war between democracy and the so-called terrorism, but rather a war between the Western colonialism and the freedom-loving nationalist and Islamist forces," the statement said.

A UN report issued last month said August was the deadliest month of 2009 for civilians because of violence from the insurgency. A total of 1,500 civilians died in Afghanistan between January and August, up from 1,145 in the same period of 2008. About 68 per cent of the deaths were caused by the insurgents, the report said.

Military deaths have also spiked. On Wednesday, a Spanish soldier was killed when a patrol vehicle drove over a mine near the western town of Herat, the Spanish Defence Ministry said.

Elsewhere, an insurgent rocket ripped through a bus on a highway in eastern Afghanistan, killing two people aboard and wounding about 25, the government said.

The militants appeared to have been aiming for a nearby police checkpoint in Ghazni province's Qarabagh district, but the rocket fell short of the target and hit the busload of civilians instead, the Interior Ministry said.

Meanwhile, American and Afghan forces battled militants in neighbouring Wardak province, killing a number of insurgents. U.S. forces spokeswoman Capt. Regina Gillis declined to say exactly how many militants died, but said it was fewer than 10. No casualties were reported among American or Afghan forces.

The troops were attacked while searching a compound used by a Taliban group believed to be organizing bomb attacks in the area, a NATO statement said.

Afghanistan's Defence Ministry said Afghan forces also killed eight militants in two separate battles Tuesday in Zabul and Wardak provinces.