Shortly before French police found five dynamite sticks in the third floor toilets of Paris’s Printemps Haussmann department store Tuesday, the AFP news agency received a tip-off from a previously unknown group.

The letter, purportedly written by a group calling itself The Afghan Revolutionary Front, has baffled experts such as Louis Caprioli, a former French anti-terror chief.

Calling for the withdrawal of French troops from Afghanistan “before February 2009,” the letter provided the location for the explosives and warned, “I assure you this is no joke, so tell the competent authorities right away or you will have blood on your hands.”

Speaking to FRANCE 24 Tuesday, Caprioli expressed doubts over whether the letter bore the stamp of Islamist extremists.

For the former counter-terror chief of the DST (Direction de la Surveillance du Territoire), the French domestic intelligence agency, everything about Tuesday’s incident – from the name of the group to the manner in which it warned the media about the explosives – was puzzling.

It’s all in the name – or is it?

The devices, which were unusable since they did not have detonators, have raised questions about the alleged group’s intention to cause harm.

“There is no will to commit the attack. And al Qaeda never warns, they just attack,” said Caprioli. The language employed, particularly the expression, “your capitalist department stores” also surprises the former counter-terror chief. “That does not sound very bin Laden-like,” he said, referring to al Qaeda chief Osama bin Laden.

Even the name, “The Afghan Revolutionary Front,” poses a problem. “The term ‘front’ is usually used by the Palestinian leftist movements and the other ultra-left movements,” he explained. It’s an investigative direction Caprioli says he’s not discounting for the moment.

Another astonishing element about the letter, which was typed on a manual typewriter and mailed to the AFP, is the shoddy French, which included numerous grammatical errors. “The form of the claim is outdated. These days, everything is done on the Internet – the methods as well as the explosives employed,” he said.

Examining the Afghan connection

Shortly after the discovery of the explosives Tuesday, French Interior Minister Michèle Alliot-Marie said the group was totally unknown by French security services and she was sceptical about the Afghan connection. In particular, she drew attention to the absence of a religious discourse in the letter, which would be typical for such a group.

But Caprioli stressed that every angle of the investigation needs to be pursued. “Everything is possible, that’s what is terrible,” he said. “On the one hand, the message does not sound credible. But the fact that Afghanistan is mentioned in the message needs to be taken seriously.”

France has more than 2,600 troops currently stationed in Afghanistan.

In a 42-minute video distributed last month, a Taliban military commander warned that France faced retribution if it did not pull the troops out of Afghanistan.

Tuesday’s incident came just two days after France hosted a meeting aimed at finding ways to bring Afghanistan out of its seemingly endless state of war, and to urge the country’s neighbouring states, in particular Pakistan and Iran, to play a more positive role.

The answers to Tuesday’s events, Caprioli stressed, would only emerge after a comprehensive investigation including forensic tests of the explosives as well as an examination of the language of the letter, which could lead analysts to either discount – or not – the Afghan connection in Tuesday’s incident.