Relatives of people who died in the terror attacks on the World Trade Center and the Pentagon are scheduled to hold a rally at the U.S. Capitol today to protest what they fear are plans by the Bush administration to delay or block their lawsuit against prominent Saudi individuals for an alleged role in financing al Qaeda.

The suit -- filed in federal court here in August against dozens of wealthy Saudi business figures, members of the Saudi royal family and leading Muslim charities -- has caused concern among U.S. officials, who believe it could damage relations with Riyadh, government sources said.

But U.S. officials say they have not decided whether to submit a motion seeking to restrict the lawsuit or take some other legal action.

U.S. officials likely would not try to block the lawsuit outright, but might seek to limit it in scope by informing the judge of the diplomatic sensitivities, international lawyers said. The suit, whose plaintiffs include about 3,000 relatives of the Sept. 11, 2001, victims as well as some survivors, seeks up to $1 trillion in damages.

David White, a spokesman for the legal team that filed the lawsuit, said the Sept. 11 families will stage the rally to express their "deep concern'' at the prospect that the government might intervene.

"Mr. President, your decision in this matter will determine whether our government stands with American families or Saudi royalty," 28 of the plaintiffs said in a letter sent yesterday to President Bush.

Among the defendants are Prince Sultan, the Saudi defense minister; and Prince Turki al-Faisal, the Saudi ambassador to Britain.