British police filed their first charges in the London terrorism investigations Wednesday, accusing a 23-year-old man of withholding information about the abortive July 21 transit attacks.

Police say that in the week after the attempted attacks, Ismael Abdurahman of southeast London had information he knew might help police capture suspects involved in "the commission, preparation or instigation of an act of terrorism."

He was charged under anti-terrorism legislation and is to attend a hearing in London on Thursday.

The charges could mark an important step forward for police seeking to build cases against the 17 people in custody in connection with the July 21 attacks, in which assailants failed in their attempts to detonate bombs on three subway trains and a bus.

The Zambian government, meanwhile, announced Wednesday that it was deporting Haroon Rashid Aswat, a British citizen of Indian descent, to Britain. President Levy Mwanawasa confirmed that the man was a suspect in the July 7 bombings in London, in which 56 people, including the presumed bombers, were killed.

The United States wants to question Aswat about possible links to a plan to establish a terrorist training camp in Oregon.

The U.S. State Department, meanwhile, advised Americans visiting Britain to "exercise caution in public places or while using public transportation" and noted British police warnings that another attack is possible.