Bamako: Mauritanian troops on Saturday clashed in Mali with al Qaeda`s north African wing, the key suspect in the kidnapping of five French and two African uranium workers in Niger, security sources said.
"The clashes began on the Mauritania-Mali border but then moved on to Malian territory at Hassissidi, about 100 kilometres (60 miles) north of Timbuktu," a Malian security source said.
"We are presently in Malian territory and engaged in full combat," added a Mauritanian security source.
However, both sources did not specify if the clashes were linked to the abductions.
Before dawn on Thursday, gunmen kidnapped an employee of the French nuclear group, Areva, and his wife, both French, and five others, including a Togolese and a Madagascan, from Satom, a subsidiary of construction giant Vinci, in northern Niger.
Security sources in Niger and Algeria said on Friday that the gunmen and their hostages had "crossed the border" between Niger and Mali and were in the Malian desert.
The kidnappers carried out an audacious and apparently well-prepared operation, seizing the victims from their homes near Areva`s uranium mine at Arlit, 800 kilometres (500 miles) northeast of Niger`s capital Niamey.
The French Foreign Ministry said it had received no claim or ransom demand and could not draw a definitive conclusion about the kidnappers, despite concerns that they might be linked to the north African wing, Al-Qaeda in the Islamic Maghreb (AQIM), which killed a French hostage in July.
That month French and Mauritanian soldiers launched an attack on a suspected al Qaeda base in the Malian desert, killing seven militants but failing to find the elderly hostage who was later murdered.
AQIM in turn called for revenge against France and labelled French President Nicolas Sarkozy an "enemy of God".
With the latest kidnappings, French nationals working for French firms in the north of Niger were evacuated on Friday towards Niamey or repatriated to France.
A group of about half a dozen Areva employees arrived on Saturday morning at Charles de Gaulle airport near Paris, following about 14 workers the day before, company spokeswoman Anne Fauconnier said.
"We didn`t feel any real tensions except for the morning when we learned that our colleagues had been kidnapped. That was a sudden shock," said Olivier Godon, 40, an Areva auditor, repatriated to France.
"When you go there, you know that there is a danger, that one morning you could wake up and find the door knocked down," he added.
AQIM has carried out several kidnappings of Westerners in the vast territory south of the Sahara stretching westwards from Mauritania across Mali and Niger. The group has also previously moved its hostages to the Malian desert.
A source close to Niger investigators said that the hostage takers had "inside people" in the security force protecting the uranium mine in Arlit.
The brother of a hostage, Daniel Larribe, echoed him, saying his sibling had "fears which unfortunately have been confirmed.
"He often told me that his work in Niger was becoming more and more difficult," he added.
For the French state-owned nuclear firm, Niger is a strategic country.
Areva has worked in Niger for 40 years and employs some 2,500 people, including until Friday about 50 expatriates.
The company extracts half its total uranium production from Arlit and the nearby Akokan mine, and nuclear power plants provide France with more than 75 percent of its electricity supply.
The Areva group hopes to put into service a giant uranium mine at Imouraren at the end of 2013, also in the north of the country.
Though Niger is among the poorest nations in the world, it is the third largest producer of uranium.