Afghan Taliban leader Mullah Omar on Wednesday rejected Afghan President Hamid Karzai's call for peace talks and scoffed at an expected US troop buildup in a rare statement issued ahead of the Muslim Eidul-Adha, the biggest Muslims' annual religious festival.

In the statement posted in English on a Taliban website, the reclusive Taliban supreme commander also called on Afghans to support the Taliban and break off ties with Karzai's government.

Karzai, inaugurated last week for his second five-year term, called for peace and reconciliation with militants. On Sunday, a presidential spokesman said that Karzai could invite militants to attend a "Loya Jirga," or traditional grand assembly.

However, the Taliban have consistently rejected calls for talks with the Afghan government, insisting that foreign troops must pull out of Afghanistan before any negotiation.

"The invaders do not want negotiation aimed at granting independence to Afghanistan and ending their invasion but they want negotiation which will prolong their evil process of colonization and occupation," the statement said.

Omar also insisted that the foreign troops were doomed to lose the war in Afghanistan, even though Washington may send more troops to quell the Taliban insurgency.

"This is a defeat which can't be averted by reinforcement and formulation of successive irrational strategies. It is better for you to choose the path of rationale instead of militarism and put an end to the occupation of Afghanistan," the statement said.

Omar's statement came as US President Barak Obama prepares to unveil his long-deliberated war strategy. On Tuesday, Obama vowed to "finish the job" in Afghanistan and is expected to announce next week whether he will send up to 40,000 more US troops to Afghanistan.

There are already around 110,000 foreign troops in Afghanistan, including 68,000 Americans.

Washington has been seeking additional troops from NATO allies as well. On Wednesday, British Prime Minister Gordon Brown told NATO Secretary-General Anders Fogh Rasmussen that he is "optimistic" that other allies will send more troops to Afghanistan.

Brown had been seeking 5,000 more troops from 10 alliance members. Britain, which has some 9,000 troops in Afghanistan, is prepared to commit an extra 500 troops.

Mullah Omar had led the Taliban regime that was toppled by the American-led invasion of Afghanistan in 2001. He has not been seen in public since.

A recent Washington Times report has claimed that Omar traveled to Pakistan's Karachi city after the end of Muslim holy month Ramazan. But the report has been rejected by Islamabad as baseless.