Federal authorities said yesterday that a man they described as a senior deputy to Osama bin Laden, the Saudi exile suspected in last month's bombings of two United States Embassies in Africa, tried on behalf of the bin Laden group in 1993 to obtain materials that could be used to develop nuclear weapons.

In one case, the authorities cited a document that they related to a proposed purchase of enriched uranium. But they did not say whether the group ever obtained the uranium.

Aside from the nuclear allegation, the authorities asserted that the bin Laden group had worked with Iran and with the Sudanese ruling party to oppose the United States, and they suggested that the United States had penetrated the bin Laden organization in 1996.

The allegations are contained in court papers unsealed yesterday that accused Mamdouh Mahmud Salim of conspiracy to murder and to use weapons of mass destruction against Americans stationed outside the United States, in Saudi Arabia, Yemen and Somalia.