KABUL, Afghanistan (CNN) --Suspected terrorist Osama bin Laden reportedly condemned Pakistan's support of the U.S.-led military campaign against Afghanistan and called on all Muslims to combat "the crusader war against Islam," the Al Jazeera television network broadcast on Thursday.
The Qatar-based news network said a letter, dated November 1, was hand-delivered to its Kabul office on Thursday. There was no confirmation that the message came from bin Laden. But Al Jazeera, an Arabic-language station, said the letter's signature appeared authentic.
The letter, written in Arabic and directed to "My Muslim brothers in the clean land of Pakistan, civilians and military," said the killing of Muslims by U.S. forces has divided the world into two groups -- those under the Christian banner led by U.S. President Bush and those under the Muslim banner.
"The Pakistani government has stood under the banner of the cross, and God said, 'Tell the hypocrites that they shall meet painful punishment, and those who take the infidels as their leaders, as opposed to taking the believers, seek power from the infidels,'" the letter said.
Islamabad has said it supports the U.S.-led campaign against terror and has allowed the United States limited use of its air space and some of its military bases. This stance has prompted Taliban supporters to protest and led Pakistan to ban rallies and restrict freedom of assembly on Thursday in an effort to crack down on civil unrest.
The alleged bin Laden letter mirrored much of this anti-American and anti-Pakistani sentiment, noting that "the crusader war against Islam has intensified, and the killing of the followers of Mohammed, peace be upon him, has increased in Afghanistan."
"God also said that those who take … the infidels as their leaders are considered infidels themselves. Supporters of Islam, this is your day to support Islam," the letter said. " Those who believe in God … shall not rest until they … defeat, by the will of God, injustice."
U.S. officials have repeatedly said the airstrikes against Afghanistan were launched because the Taliban refuse to hand over bin Laden, who they believe was behind the September attacks against the United States that killed nearly 5,000 people.
The letter sent to Al Jazeera focused on the U.S. action in central Asia, equating the attacks on Afghanistan to attacks on all Muslims.
"Your stand against injustice helps us and strengthens us," the letter said. "The prophet Mohammed said, 'Muslims are brothers, they are not unjust to each other, let each other down or sell each other out.'"
The letter is signed, "Your brother, Osama bin Laden."