Somalia, which has had no functioning government since 1991, is the world's top piracy hotspot. The latest incidents bring to 44 the number of attacks off its coast this year. Most occurred in the Gulf of Aden, Choong said.
"Early detection allowed all three ships to report to IMB and take quick action to escape," said Choong, who heads the IMB's piracy reporting center in Kuala Lumpur. He said the situation was still grave despite increased patrols by warships from a multinational coalition in the area.
The Chinese-owned ship, sailing under the flag of the Caribbean island state of Saint Vincent and the Grenadines, was passing through the gulf Friday when crew noticed a blue tug identified by the IMB as a suspected pirate vessel, Choong said.
The crew raised the alarm after a speed boat from the tug headed toward the ship, he said. Four pirates armed with rocket-propelled grenades and automatic weapons started firing, but the ship escaped after it increased speed and the crew threw objects at the pirates during the chase, he said.
On Saturday, six pirates armed with rocket-propelled grenades attempted to ambush a Singaporean tanker in the gulf, Choong said. The tanker increased speed and changed course, leaving the attacking boat rolling heavily and four pirates fell into the sea, he said.
The pirates later resumed chase and the ship captain contacted the IMB, which sought help from the coalition naval force, he said. The pirates gave up their chase before a coalition warship could reach the scene, he said.
The next day, pirates in two speed boats chased a Thai bulk carrier but it also managed to evade the pirates and headed toward Yemen's coast, Choong said.
Nobody on board the ships was injured in the incidents.
The attacks came after pirates hijacked an Egyptian cargo ship and a French sailboat last Wednesday. Ten vessels have been seized in the region since July 20.
The Gulf of Aden, which connects the Red Sea and the Indian Ocean, is one of the world's busiest waterways with some 20,000 ships passing through it each year. The surge in pirate attacks has prompted the U.S. Naval Central Command to establish a security corridor in the gulf patrolled by the international coalition of warships.