- France to hand over 11 Somali pirates to Kenya
* Europe to send more ships to reinforce anti-piracy mission
By Sophie Hardach
PARIS, April 16 (Reuters) - France plans to hand the 11 Somali pirates seized in a naval raid this week to Kenyan authorities, as Europe is ramping up its mission to fight a growing number of attacks in the waters off East Africa.
Somali gangs in small boats are challenging the world's military powers with ever more daring strikes along major trade routes, expanding their operations towards the coast of Kenya and the Seychelles islands, defence officials said.
"It's a difficult task and the pirates are very active, so the more ships there are, the better," a source at the Council of the European Union in Brussels told Reuters by telephone.
Sweden will send two frigates and a refuelling vessel to reinforce the EU's anti-piracy mission in May, while the Netherlands and Norway will each deploy a vessel to the area in August, the source said.
After falling sharply earlier this year, the number of attacks in the Gulf of Aden and the Indian Ocean more than doubled to 24 in March from 11 in February, armed forces spokesman Christophe Prazuck told a news conference on Thursday.
There have been 18 attacks in April so far.
Known as "Operation Atalanta", the EU's mission patrols the area with aircraft and vessels. French forces taking part in the operation captured the 11 pirates, their small mothership and two skiffs some 560 miles east of the Kenyan port of Mombasa.
Pirates from lawless Somalia, some of whom have said they turned to hijacking and hostage-taking because overfishing deprived them of their traditional livelihood, are presenting a legal and diplomatic as well as military challenge.
Kenya has agreed to deal with the detainees under accords with the European Union, Britain and the United States, but it has said it cannot try all pirates.
Several pirates seized after hijacking French ships and taking hostages, including a group arrested last week, are facing trial in France -- but some have demanded they be sent back to Somalia, arguing their transfer to France was illegal.
Somalia, where Islamist militants are fighting the government, has not had an effective government since 1991 and is unable to tackle the problem of piracy, onshore or offshore.
Naval forces from the United States, Europe and Asia have been deployed to protect merchant ships off the Horn of Africa after rampant piracy sent insurance costs soaring.
French defence officials had hoped the international show of force, which includes a NATO mission, would deter pirates -- attacks fell to 23 in December and 17 in January, after spiking at 37 last November.
(Editing by Jon Boyle)