Kuala Lumpur: A Singapore-managed product tanker with valuable gasoline cargo has gone missing and is suspected to have been hijacked by pirates while at anchor off Lome, Togo, a maritime watchdog said on Tuesday.

Potengal Mukundan, director of the London-based International Maritime Bureau (IMB), told a news agency international warships and navies from neighbouring countries have been alerted and are searching for the ship, which has 24 crew members and was reported missing by the operators on Tuesday.

Mukundan, who is in the Malaysian capital Kuala Lumpur for a series of meetings with industry and government players, said in similar past cases the pirates would transfer the gasoline cargo to other ships and sell it.

"Here we have criminal gangs whose main purpose is to steal multi-million cargo which is gasoline as it has a ready market. It is very easy to dispose of it. There has been an underground trade in the Gulf of Guinea for decades."

Mukundan said so far in 2012 there have been 19 attacks off the Gulf of Guinea on the west coast of Africa, with two vessels hijacked. Forty two crews have been taken hostage, two crew members killed and two kidnapped by pirates.

IMB urged ship owners and the international community to remain on guard against piracy in the high risk area including off Somalia, Southern Red Sea, the Gulf of Oman, Mozambique Channel and the Gulf of Guinea.

Worldwide, there have been 121 attacks and 13 hijackings in 2012. Out of these, 51 attacks and 11 hijackings have taken place off Somalia, with 158 crew taken hostage, IMB said.

"Although the number of hijackings are lower than they were this time last year, the number of attacks indicate the pirates are still there," the IMB director said.

Mukundan painted a grim picture for the rest of the year and warned the safety of seafarers continued to be threatened by pirates and urged ship masters and owners to alert IMB of any incidents and of suspicious vessels.

"The indications we have is that there will be similar level of hijackings worldwide in 2012 compared to 2011 with Somalia being the top hot spot," he said. There were 45 hijackings in 2011.

Mukundan said while more international naval assets should be deployed to fight piracy, there should also be assistance programmes developed in Somalia.

Kalashnikov-wielding Somali pirates prowl far out across the Indian Ocean from their bases in war-torn northern Somalia, seizing foreign ships which they hold for several months demanding multi-million dollar ransoms.