SOMALI (Bloomberg) — Somali pirates hijacked a UK- flagged chemical tanker and its 26 crew in the Gulf of Aden last week, the first successful attack on a merchant ship in the heavily patrolled sea channel in almost six months.

The St. James Park had registered its position with the European Union anti-piracy force though it hadn't joined a group transit, John Harbour, a spokesman for the force, said in a telephone interview. It was seized due north of the Somali port of Boosaaso, he said.

Some 20 warships from the EU, the North Atlantic Treaty Organisation and other countries patrolling the waters off Somalia have concentrated on the Gulf of Aden, a chokepoint leading to the Suez Canal that's used by 30,000 ships a year carrying about a 10th of world trade. The last hijacking along a 500-mile security corridor set up by the navies was in July.

While Somali pirates have attacked ships 214 times this year and seized 47, according to the International Maritime Bureau, all successful attacks since the end of the summer monsoon were in the Indian Ocean, where fewer commercial ships pass. The area is too vast for navies to patrol effectively.

Somali pirates now hold nine ships and 237 sailors for ransom, Harbour said.

The St. James Park was sailing to Thailand from Spain, and is now believed to be heading for the eastern coast of Somalia, Andrew Mwangura, head of East Africa Seafarers' Assistance Programme, said by phone from the Kenyan port city of Mombasa.

Its 26-man crew includes Russians, Filipinos, Bulgarians, Indians, Turks, Ukrainians, a Georgian and a Pole, though no Britons, the EU said. The ship is owned by Philbox Ltd, the EU said. There was no answer at a London telephone number listed under that name at Companies House.

Pirates have also hijacked the bulk carrier Navios Apollon as it was sailing in the Indian Ocean, 240 nautical miles east- northeast of the Seychelles, the Greek government said.

The Panama-flagged Navios Apollon, carrying a cargo of fertiliser, has a Greek captain and 18 Filipino crew members; it was sailing from Florida to India, a spokeswoman for the Citizen Protection Ministry in Athens said in a telephone interview.

The 2000-built vessel, with a carrying capacity of 52,073 deadweight tons, belongs to the Angeliki Frangou-led Navios Maritime Partners.

No further details were available, a spokeswoman for Piraeus-based Navios said by telephone.

Pirates have also released two ships this week, the Chinese bulk carrier De Xin Hai and the Singapore-flagged container ship Kota Wajar.