By Agence France-Presse
The IMB said in its latest quarterly report that 42 instances of piracy on the high seas were recorded in July-September.
"With just 42 attacks worldwide this quarter, maritime piracy is at its lowest since 1996," it said.
The bureau's Kuala Lumpur-based Piracy Reporting Centre recorded 141 incidents from January to September, a 25 per cent drop from the same period in 2015.
"The IMB is encouraged by the efforts of national and international authorities and the shipping industry to keep piracy down," it said.
But it cautioned that pirate attacks involving hostage-taking, particularly near Nigeria, remained a problem and advised shipmasters and response agencies to stay vigilant.
World piracy has been on the decline since 2012 after international naval patrols were launched off East Africa in response to a spate of violent assaults by mostly Somali-based pirates.
There have been no attacks off Somalia so far this year, according to the IMB.
As the Somali hotspot went cold, the IMB's attention shifted to Indonesia, which saw piracy rise sharply in 2015, typically involving low-level strikes on vessels transporting fuel.
But the IMB report said attacks in Indonesian waters had "plummeted" to 33 in the first nine months of this year from 86 in the same period in 2015.
"Patrols by the Indonesian Marine Police appear to be working," the report said.
The 33 Indonesia attacks in January-September remained the highest number in the world, followed by 31 off Nigeria.