Due to the turmoil in Libya, members of Al-Qaeda in the Islamic Maghreb (AQIM) have "gained access to weapons, either small arms or machine-guns, or certain surface-to-air missiles which are extremely dangerous because they pose a risk to flights over the territory," said Gilles de Kerchove.

At a news conference marking the 10th anniversary of the 9/11 attacks in the United States, de Kerchove said that while the threat of strikes by mainstream Al-Qaeda followers had decreased, AQIM was taking root both on the Arab peninsula and in Africa, posing a mounting threat.

"It is a group that is Africanising and seeking to extend its area of influence," he said.

Like other Al-Qaeda affiliates in Pakistan and elsewhere, AQIM had gained support among locals by using ransom money and possibly drug-related income to fund social services unavailable from cash-strapped African governments.

It had extended its area of action from northern Niger, Mali and Mauritania to northern Nigeria and as far south as Senegal, he said.

To put a brake on any further extension of its influence, European Union nations needed to help African countries such as Chad and Niger to reintegrate the hundreds of thousands of migrant workers who have fled home from Libya in the past months. Mali alone faced the return of 210,000 people, he said.

Plans were underway also to aid information-gathering and counter-terror centres in Algeria and Mauritania, and to back Malian efforts to redeploy seven to 10 military bases in its remote barren north as well as provide basic services for the population there.

A Nigerien government source said that the fugitive ex-Libyan leader was not in the group of 11 Libyans.

"Moamer Kadhafi was not part of the delegation that arrived in Niger, which consisted of three Nigeriens: Agaly Alambo and two of his brothers and 11 Libyans, among them Mansour Daw," the government source said.

"The 11 Libyans will be housed in Niamey and we have taken measures to this effect," added a security source.

The Libyans arrived in the northern Niger city of Agadez escorted by Alambo, a historical leader in Niger's Tuareg rebellion with close ties to Kadhafi.

"In any case, these people who came with Agaly (Alambo) are neither Kadhafi's sons nor his close relatives," a Tuareg source told AFP on condition of anonymity, adding that all had since reached the capital Niamey.

Alambo, head of the Niger Movement for Justice, the country's main Tuareg rebel group since 2007, had been living in Libya since Kadhafi brokered an end to his fight against Niamey in 2009.

When Western powers backed Libya's own rebel movement earlier this year, Alambo recruited hundreds of former rebels from Niger to fight alongside Kadhafi, whom many Tuaregs across the region see as their champion.

Last week, a Tuareg source said that people close to Kadhafi had arrived in Agadez in April with suitcases full of money to recruit "hundreds" of young people.

The source said about 1,500 Tuareg ex-rebels had fought for Kadhafi.

But since the fall of Tripoli to fighters loyal to Libya's National Transitional Council, hundreds of Tuareg fighters have returned to Niger, while about 500 withdrew to Sirte, Kadhafi's hometown.

Niger last month formally recognised the NTC as its neighbour's only legal authority and urged the new leaders to safeguard the security of foreigners living in Libya.

Thousands of Tuaregs had taken refuge in Libya following the rebellions which have hit Mali and Niger over the past two decades.

Niger's President Mahamadou Issoufou, elected in March, was considered an ally of Kadhafi and the two last met in Tripoli in February.