Hong Kong (CNN) -- Sea piracy has fallen to its lowest level worldwide since 2008, as policing by international naval forces has deterred pirates operating in the waters off Somalia, new figures from the piracy watchdog show.
The International Maritime Bureau (IMB) said there were 233 actual and attempted attacks on vessels globally in the first nine months of 2012, compared with 352 in the corresponding period last year.
The number of attacks by Somali pirates has fallen dramatically, with 70 attacks by the end of September, down from 199 in the same time frame in 2011 and the lowest number since 2009, according to the report, which was released on Monday.
Pottengal Mukundan, director of the IMB, said the decline was a reflection of the pre-emptive and disruptive counter-piracy tactics used by international navies, as well as deployment of on-board security measures like armed guards.
"It's good news that hijackings are down, but there can be no room for complacency; these waters are still extremely high-risk and the naval presence must be maintained," he said.
"There is no alternative to their continued presence as long as Somali pirates threaten major trade routes in this region," Mukundan added.
Worldwide, pirates have killed six and taken 448 crew hostage in 2012, according to the report.
It noted piracy had increased in West Africa, off the coasts of Nigeria, Benin and Togo.
Attacks there were often violent and targeted tankers carrying refined oil products that can be easily sold, it added.
"There continues to be a serious problem with under-reporting of attacks in this area," Mukundan said.
"This may be because of a fear of reprisals or a feeling that little will change as a result."
In Asia, the waters off Indonesia were most prone to pirate attacks, with 51 incidents, up from 30 in 2011.
The report said the attacks were usually opportunistic and targeted ships at anchor.