KUALA LUMPUR, Malaysia (AP) -- A navy coalition warship has been dispatched to track three vessels that were hijacked this week by armed pirates in an unprecedented series of attacks off the coast of Somalia, officials said Friday.

The Iranian, Japanese and German vessels and their 57 crews members were seized in the Gulf of Aden on Thursday.
A multi-coalition naval force, based in the region, is monitoring the movement of the ships, said Noel Choong, the head of the Kuala Lumpur-based piracy center of the International Maritime Bureau.
""All the three ships are still moving and appear to be heading toward Somali territorial water. A warship has been dispatched to monitor and track the vessels,"" he told The Associated Press.
The naval force includes the United States, France, Germany, Pakistan, Britain and Canada, which currently holds the rotating command. No other details were immediately available.
Pirates on Thursday seized an Iranian bulk carrier with 29 crew and a Japanese-operated chemical tanker with 19 crew. Then, a German-operated cargo ship with 9 crew, flying the Antigua and Barbuda flag, was hijacked nearby, he said.
The attacks came two days after a Malaysian palm oil tanker with 39 crew was seized in the vicinity and raised the number of ships hijacked in the Gulf of Aden to seven since July 20.
Choong said there has been no communication so far with any of the four vessels hijacked this week.
He said little can be done at this stage without endangering hostage safety, with pirates likely to demand ransom for the release of the ships and crew later.
""Somalia has no central government. We are worried that more may join the pirates to hijack ships because it's very lucrative and there is no deterrent,"" he said.
""The United Nations is the only agency that can stop this menace. The international community has to agree to find ways to solve this worsening problem. That is the only way forward,"" he said.
Choong said this week's attacks have generated huge alarm among seafarers using the Gulf, a busy waterway connecting the Red Sea and the Indian Ocean.
Somalia is the world's piracy hotspot, with 35 attacks now. Twenty-nine of those were in the Gulf of Aden, he said.
Somalia has not had a functioning government since 1991 and foreign vessels are frequently seized for ransom by armed pirates armed, making it difficult and expensive to deliver aid to the impoverished region.
In June, the UN Security Council voted to allow international warships to enter Somali waters to combat the problem. But its 1,880-mile coastline — the longest in Africa — remains virtually unpoliced.