PARIS — Islamic militants are not the main focus of a French police investigation into the mysterious planting of dynamite in a Paris department store.

France immediately ordered beefed-up security following Tuesday's bomb scare, claimed by a previously unknown group that demanded the withdrawal of France's 2,800 troops in Afghanistan.

The pack of old dynamite sticks found at the Printemps store lacked detonators and experts said the incident didn't fit the typical operations of Islamist groups like al-Qaida. Still, the discovery renewed concern over the risks of terrorism, especially during the vulnerable holiday season, and rattled shoppers and store employees.

French Interior Minister Michele Alliot-Marie met today with police and intelligence chiefs and representatives from major stores, transit networks and Paris airports. And security guards at Printemps checked customers' bags.

The scare was claimed by the "Afghan Revolutionary Front," a name not previously known to French police and intelligence officials. A letter sent to a French news agency warned that if French troops are not pulled from Afghanistan before the end of February "we will go back into action in your big capitalist stores and this time without warning."

Defense Minister Herve Morin, speaking today on RTL radio, said the letter didn't fit the profile of Islamic militants.

The incident renewed concerns that France could be targeted for its role in both the NATO effort to stabilize Afghanistan and the U.S.-led effort to fight al-Qaida and the Taliban.