Smugglers may be selling sophisticated Libyan army weapons to Al-Qaeda's offshoot in north Africa's Sahel region, Spain warned Thursday after a US-European security meeting in Madrid.

US Homeland Security chief Janet Napolitano and European powers pondered how to stop the arms reaching Al-Qaeda in the Islamic Maghreb (AQIM), Interior Minister Alfredo Perez Rubalcaba said after the talks.

The AQIM group is active in the Sahara desert and Sahel scrubland to the south -- an area nearly the size of Australia stretching from western Mauritania through Mali and Niger.

It has carried out kidnappings of foreigners and staged attacks in the region.

"All of us who sat around the table know AQIM very well. There is a circumstance that worries us at the moment and that is that the Libyan conflict is affecting AQIM," Rubalcaba told a news conference at the El Pardo palace outside Madrid.

"What seems especially negative to us is the possibility that arms belonging to the Libyan army, or what is left of it, could fall into the hands of the terrorists," he added.

"There is arms trafficking at the border between Libya and Mali and this has to worry us because it could at this moment be supplying sophisticated weapons, which are therefore dangerous, to Al-Qaeda in the Islamic Maghreb."

The meeting gathered Napolitano and the interior ministers of the G6 largest European Union nations -- Britain, France, Germany, Italy, Poland and Spain.

"There is a problem with arms that are going from Libya, probably to Mali," Rubalcaba said.

"If we don't do anything, AQIM could take advantage of this situation to grow, and if AQIM grows so will the risks faced by Europe and the United States," Rubalcaba said.

AQIM, which has its roots in Algeria, has camps in Mali which it uses as a launchpad to carry out armed attacks and kidnappings in the Sahel desert region where the group is also involved in drugs trafficking.

Rubalcaba said it was agreed at the meeting that the interior ministers and foreign ministers of the six largest European nations would hold talks on how to step up the fight against AQIM.

They also agreed that Europe would work more closely with the African Union on the issue, he added.

"It is very difficult to do anything in Africa unless you work with the African Union," the minister said.

Libya has been wracked by a civil war since a violent uprising against Moamer Kadhafi, in power for over four decades, swept the country four months ago.

The G6 represents three quarters of the EU population. The informal group was set up by Britain and France in 2003 to provide a forum for big EU nations to discuss issues of law and order and immigration.

The US and European policymakers also discussed ways to boost the fight against organised crime including drug trafficking, prostitution and money laundering.

Before the start of the meeting, Rubalcaba and Napolitano signed an agreement to boost Spanish-US scientific and technological security cooperation, the interior ministry said in a statement.

"The agreement stresses the importance of protecting key infratructures to better protect the flow of goods and citizens between both countries," the ministry said.

Other participants included the EU's home affairs commissioner, Sweden's Cecilia Malmstrom, the bloc's counterterrorism coordinator, Belgium's Guilles de Kerchove, and US Deputy Attorney General James Cole.