PARIS - Police found dynamite in a Paris department store yesterday, a bomb scare during the holiday season that was accompanied by an unknown group's demand for the withdrawal of French troops from Afghanistan.

The five relatively old sticks of dynamite planted in the men's department at the elegant Printemps store were not attached to a detonator and did not pose a risk of explosion, authorities said.

After evacuating the jam-packed store in the heart of the downtown shopping district about 11 a.m., police used bomb-sniffing dogs to find the explosives, which a warning letter sent to a French news agency had said were in a third-floor bathroom.

Built in 1865, the upscale Printemps draws 100,000 customers a day, a quarter of them tourists. During the holidays, crowds flock to ornate Christmas displays in the windows of the store and the Galeries Lafayette next door.

The letter was signed by the "Afghan Revolutionary Front," a group that is "totally unknown" to French intelligence services, Interior Minister Michele Alliot-Marie told legislators in comments in the National Assembly.

Despite the rhetoric about Afghanistan, the type of explosives, the language of the communique and other details were not consistent with previous activity by Islamic extremist groups, anti-terrorism officials said.

"We must be wary of the indications in the letter that could orient investigators toward false leads," Alliot-Marie said at the scene, where hundreds of police officers oversaw an orderly evacuation of the store. She announced that security would be stepped up in Paris and other cities during the holidays.

The incident came during a heightened terrorist alert in Europe. On Friday, French police arrested two suspects tied to a group in neighboring Belgium that allegedly sent militants to train and fight in Afghanistan. Belgian police rounded up an additional 14 suspects because of fears that a suspect recently returned from Afghanistan was preparing a suicide attack.

Security guards at Printemps' three-store complex on the stately Boulevard Haussman were on alert because a phoned bomb threat against the chain was delivered last week to Agence France-Presse, the news agency reported.

Yesterday, the news agency advised police after receiving the letter in the morning from the purported Afghan group. The text released by the news agency described the location of the explosives and warned authorities that they would have blood on their hands if they did not act.

"Make this message reach your president that he should withdraw his troops from our country [Afghanistan] before the end of February 2009 or we will return to action in your big capitalist stores and this time without warning you," the letter declared, according to the news agency.

It is very unusual for al-Qaeda or other Islamist groups to advise authorities of the presence of bombs ahead of time, experts said.