Pirate activity has soared in southeast Asia, according to the International Maritime Bureau’s (IMB) latest report.

While global attacks have fallen for the third consecutive year, the IMB’s Piracy Reporting Centre says gangs armed with knives and guns are making southeast Asian waters increasingly dangerous.

Small tankers carrying gas oil or marine diesel oil are particularly vulnerable. Pirates usually board at sea, holding the crew hostage while they unload the cargo.

Of the six vessels hijacked worldwide in the third quarter of this year, five were in southeast Asia.

“We advise small tankers in particular to remain vigilant in these waters and report all attacks and suspicious small craft to the IMB’s Piracy Reporting Centre,” Director Pottengal Mukundan said.

The Regional Co-operation Agreement on Combating Piracy and Armed Robbery against Ships in Asia (ReCAAP) reported a 50% increase in incidents for the first half of this year.

Between January and June, 90 attacks were reported, compared with 61 in the corresponding period last year.

But ReCAAP says the third quarter has seen improvements.

“There has been a decline in the number of such incidents reported in August and September, probably due to the ongoing collaborative efforts by the maritime enforcement authorities and the shipping industry,” it says.