PARIS (Reuters) - A French warship thwarted an attack by Somali pirates on a cargo ship in the Gulf of Aden and arrested eight men, the French military said on Friday.

The French frigate was patrolling the seas off Somalia as part of a European Union mission against rampant piracy in the region when it received a distress signal on Thursday from a Panamanian-registered boat that was being pursued by pirates.

Christophe Prazuck, a spokesman for the French armed forces, said the pirates fled when the frigate first approached and were eventually captured when they made a second attempt to seize the S. Venus cargo ship some hours later.

"Resistance was impossible when faced by a well-armed warship," Prazuck told LCI television, adding that the French forces had found a rocket launcher, assault rifles and boarding ladders on the pirate's vessel.

The operation happened some 80 km (50 miles) from the coast of Yemen and the eight men seized by the French will be taken to nearby Somalia for trial.

"There is a diplomatic agreement whereby the Somali authorities are committed to prosecuting and punishing (pirates)," Prazuck said.

Piracy off Somalia, one of the world's busiest shipping areas, has soared over the past year, earning the pirates millions of dollars of ransom payments and pushing up maritime insurance rates.

In a bid to deter the bandits, the European Union set up an anti-piracy naval task force under British command last month involving warships and aircraft from several nations in the first such naval operation of its kind.

France has been particularly active in the fight and has arrested 29 pirates in four operations since last April, some of whom are in France awaiting trial.