NAIROBI, Kenya (AP) — Last week, pirates seized a Kenyan-flagged fishing vessel off the Somali coast for possible use as a "mother ship" to launch more attacks, a maritime official said on Tuesday.

And a French frigate operating off the coast of Somalia has captured 35 pirates in just 48 hours, the French Defence Ministry said in a statement on Sunday.

It was the biggest such haul since European Union navies started patrolling the Gulf of Aden and western Indian Ocean in December 2008 in an effort to end a spate of hijackings in the busy shipping lanes.

The French frigate, the Nivose, seized four "mother ships" and six skiffs in various sweeps on pirates over the past two days, with a Spanish aerial patrol and two helicopters identifying and tracking down the pirates.

Andrew Mwangura of the East African Seafarers' Assistance Programme said pirates captured the Spanish-owned FV Sakoba last week about 400 miles east of Dar es Salaam.

"I think the pirates have taken her, now they are using her as a mother ship to attack other ships," he told Reuters.

Mwangura said ten Kenyans, one Spaniard, one Pole, one Cape Verdean, a Namibian and two Senegalese made up the ship's crew. A director of the company that operates FV Sakoba was heading to Kenya to negotiate its release.