* Tripoli's neighbours worried over Libya turmoil
* France's Mali push made southern Libya an Islamist hub
By Patrick Markey
TUNIS, Oct 6 (Reuters) - The U.S. raid to snatch a top al Qaeda suspect off a Tripoli street confirmed what many Libyans already feared: Post-revolution chaos has made their vast North African country a haven for Islamist militants with transnational ambitions.
Two years after a war backed by the West ousted Muammar Gaddafi, Libya is still fragile, its government weak and its army unable to control vast tracts of territory, where rival militias battle over a share of the country's spoils.
On Saturday, Nazih al-Ragye, better known by the cover name Abu Anas al-Liby, wanted in the bombings of U.S. embassies in Africa 15 years ago, was grabbed by ten men as he made his way from prayers in the south of Tripoli.
Four cars swooped on Liby as he returned home and men with Libyan accents grabbed him, according to his family, and bundled him into a van which sped off. U.S. officials say he is now being held in outside the country.
Some security experts said the seizure of such a high-ranking militant suspect in the Libyan capital highlighted how successive al Qaeda-linked groups are establishing bases far from its Pakistan-Afghanistan centre.
While Liby was a former exile reported to have returned home last year, increasingly, analysts say, Libya has attracted foreign militants with its weak central authority, uncontrolled land and porous borders to sub Saharan Africa that allow easy flow of arms and men to the region's hotspots.
"Libya has been seen as a haven for all kinds of radical groups in the absence of a central government that can really control the territory," Prof. Dirk Vandewalle, a Libya expert and author at Dartmouth College who just returned from Tripoli.
"Certainly, the United States sees Libya as a crucial territory to control whatever terrorism is taking place not just in Libya but also in the Sahel and even into sub Saharan Africa."
Since Gaddafi's fall, Islamists, including elements of al Qaeda, have used Libya to smuggle out weapons and a base for fighters. North Africa is home to Al Qaeda in the Islamic Maghreb and other Islamist affiliates who either cooperate with the network or sympathise with its ideology.
That influence was clear when Islamist militants were blamed for the attack a year ago on the U.S. consulate in the eastern Libyan city of Benghazi during which the U.S. ambassador was killed.
Over the past two years, weapons have made it into Egypt, Mali and Syria from Gaddafi's former stockpiles, and into the hands of rival militias and former Libyan rebels who refuse to disarm, saying they want to see more of Libya's wealth.
Its turmoil makes Libya's central authority precarious even two years after the revolt, as Prime Minister Ali Zeidan fends off pressure from rival tribes and protesters seeking more regional autonomy in the east and south of the country.
Symbolic of the disarray, for the last two months, armed protesters have taken over key ports to demand more autonomy for their eastern region, cutting the OPEC country's production by half from the usual 1.4 million barrels per day.
Last week armed mobs also tried to storm the Russian embassy after reports a Ukrainian woman murdered a Libyan officer, forcing diplomats to evacuate after Tripoli said it could not guarantee their safety.
ISLAMISTS ACROSS THE MAGHREB
Libya's turmoil worries its neighbours across North Africa, feeding concerns Libyan territory may give fertile ground for Al Qaeda in the Islamic Maghreb and other Islamist militants who are increasingly cooperating, according to security analysts.
Security officials say lawless southern Libya has become more of a haven for al Qaeda-linked fighters after French-led forces drove them from strongholds in northern Mali this year, killing hundreds in its military campaign there.
Algerian security officials blamed militants who launched operations from Libya for the January attack on the Amenas gas plant near the Libyan border, killing more than 30 foreign workers and making foreign oil companies start to reassess operations in North Africa.
"The capture of a major al Qaeda figure will not have a big impact on the overall situation as long as the state is still not visible," one Algerian security source told Reuters. "Armed groups are filling the vacuum."
The man blamed for the Amenas attack, Mokhtar Belmokhtar, threatened to hit French interests this year, announcing his fighters would join forces with MUJWA, an Islamist group that was scattered by the French offensive on Mali.
In neighbouring Tunisia, the Islamist-led government has also designated a local hardline group officials linked to al Qaeda, Ansar al-Sharia, as a terrorist organisation after blaming it for the assassination of two opposition leaders.
What Liby's alleged role was is still not clear. His son, Abdullah al Ragye, denied his father had taken part in the bombings of the U.S. embassies.
Liby was described in an 2012 U.S. Congressional report as "a builder of al Qaeda's network in Libya", according to the Long War Journal, which documents what is known in the U.S. as the War on Terror.
Libya's porous security would have given an al Qaeda suspect broad communication with other Islamists and al Qaeda affiliates, journal Senior Editor Thomas Joscelyn said.
"It is not just one or two," he said. "there are whole a host of known al Qaeda personalities he could have been working with and known al Qaeda linked groups he could be working with."
Libya's government, wary of an Islamist backlash, described the capture of a Libyan citizen on its soil as a "kidnapping" and asked Washington for an explanation. Some Libyans were already bracing for an Islamist reaction.
"There will be a reaction to take revenge because he is an important al Qaeda figure," said Abdul Bassit Haroun, a former Libyan militant. "To show them that the arrest of any person will cost a lot."