Filipinos held by Somali pirates

The Gulf of Aden is among the world's most perilous shipping channels

A chemical tanker with 21 Filipino crew members on board has been hijacked by Somali pirates, according to maritime officials.

The ship was in the Gulf of Aden, en route to Asia, when it was seized on Monday afternoon.

There have been dozens of attacks and hijackings in the region this year, making it one of the most dangerous sea lanes in the world.

The EU is launching an anti-piracy security operation in the area.

The Philippine-flagged Stolt Strength was seized "on Monday afternoon, but we are now tracking its whereabouts", Andrew Mwangura, of the Kenyan branch of the Seafarers' Assistance Programme, told AFP news agency.

He said all 21 crew members on board were Filipino.

"We are yet to establish where the ship was heading and what it was carrying," he said.

The Stolt Strength is reported to be managed by Victoria Ship Management in Manila but on long-term charter to Stolt-Nielsen.

The ship was seized nearly two months after its sister ship, the Stolt Valor, was taken in the same area.