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NEW YORK (CNN) -- Terrorism suspect Osama bin Laden tried to develop chemical weapons to use against U.S. troops in the Persian Gulf, a high-ranking CIA official has said.

Bin Laden's drive to obtain the chemical weapons could be linked to the Al-Shifa pharmaceutical plant in Khartoum, Sudan, which was bombed by the United States in late August, said John Gannon, chairman of the CIA's National Intelligence Council.

Gannon made the comments Monday during a conference on biological and chemical weapons at the Hoover Institution in California.

"We know that bin Laden's organization has attempted to develop poisonous gases that could be fired at U.S. troops in the Gulf states," Gannon told the conference attendees.

Gannon said the Sudan plant had known ties to bin Laden. The discovery at the plant of a precursor to the deadly gas known as VX fit into "an ominous pattern we had been piecing together against bin Laden and his network," Gannon said.

In court documents unsealed earlier this month, U.S. prosecutors charged that bin Laden had made efforts to obtain the components of chemical weapons as early as 1993.

Bin Laden was charged with masterminding the August bombings of the U.S. embassies in Kenya and Tanzania that killed 263 people. Several of his alleged co-conspirators are in custody in New York and in Germany, but bin Laden remains at large.

Since 1996, the exiled Saudi businessman has lived in Afghanistan, where he operates training camps for his alleged terrorist followers. Those camps were the targets of a U.S. missile attack several weeks after the embassy bombings.

Washington has offered a record $5 million for bin Laden's arrest and conviction for the bombings.

U.S. prosecutors have said in court documents that bin Laden and members of his militant Islamic organization, Al-Qaida, had plotted attacks against U.S. troops in the Gulf region. Gannon took the allegations a step further, charging that chemical weapons would have been used in the attacks.

Bin Laden, believed to be the sponsor of a worldwide terrorist network, issued death threats against U.S. personnel as part of his campaign to drive the United States out of Saudi Arabia following the Gulf War in 1991.

According to a New York representative of Afghanistan's ruling Taliban, the U.S. government has failed to present evidence that would prove bin Laden's involvement in the embassy bombings.

The Taliban had said that it may put bin Laden on trial in Afghanistan if the United States could provide evidence of his involvement. It imposed a November 20 deadline for receipt of that material.

The Taliban representative, Noorullah Zadran, said that bin Laden has been under "observation" by the Taliban since the allegations of his involvement in the bombings were made, but that situation could not continue "indefinitely."

Correspondent Peter Bergen contributed to this report.