A group claiming to represent Al Qaeda in Europe repeated threats against Britain, Italy, Bulgaria and other nations with forces in Iraq in a Web statement Tuesday.

But the statement denied that the group, calling itself Abu Hafs al-Masri Brigade Europe (search), had demanded that Italy withdraw its troops from Iraq within 15 days. The ultimatum, also signed Hafs al-Masri Brigade, was posted on the Web on Sunday.

Tuesday's statement was one in a series of claims and counterclaims in recent days that illustrate the difficulties of determining the authenticity of such Web threats or whether those that post them have any ability to carry them out.

The Abu Hafs al-Masri Brigade takes its name from a top Al Qaeda lieutenant who was killed in a U.S. airstrike in Afghanistan in 2001. It has claimed responsibility for a number of attacks on Western targets, including the March 11 train bombings (search) in Spain.

Counterterrorism experts question whether the group has any agents capable of launching attacks and say some of its claims are obviously false or exaggerated.

Italy and other European countries face heightened alerts after the expiration on July 15 of a three-month truce offered by Al Qaeda chief Usama bin Laden to European countries if they left Iraq, Afghanistan and other Muslim countries.

Tuesday's Web threat echoed one on Friday that said: "From here in Italy, and from Britain and Bulgaria, and all European countries, we call on all our people to mobilize and prepare to engage in the battle, a new type and style of battle. Prepare to shed blood, let us make it an endless bloody war."