Indonesia has accused the Vietnamese coastguard of ramming one of its vessels to block the interception of a boat fishing illegally, as a senior minister announced a return to sinking foreign trawlers.
The clash in the South China Sea at the weekend saw Jakarta summon Vietnam's ambassador on Monday, after the navy detained a dozen Vietnamese fishermen.
"The actions taken by the Vietnamese coast guard ship endangered the lives of officers from both countries and is not in accordance with international law or the spirit of ASEAN (Association of Southeast Asian Nations)," Indonesia's foreign ministry said.
Jakarta claims the area in the southernmost reaches of the South China Sea as its exclusive economic zone – waters where a state has the right to exploit resources.
The navy said two Vietnamese coast guard ships tried to prevent the apprehension of an illegal fishing boat by ramming its vessel.
The fishing boat sank possibly due to an accidental collision, Indonesian authorities said without elaborating.
A dozen fishermen were detained and remain in Indonesian custody.
Two others escaped detention by jumping into the water. They were picked by the Vietnamese coast guard, which then fled, the navy said.
Video circulating on social media purported to show a Vietnamese patrol boat ramming the left side of the Indonesian vessel as the armed navy crew shouted expletives.
Indonesia, the world's biggest archipelago nation, has been trying to stop foreign vessels fishing illegally in its territory, claiming it costs the economy billions of dollars annually.
It turned to a campaign of blowing up captured foreign boats as a deterrent.
Hundreds of detained foreign fishing vessels have been sunk, including many Vietnamese boats –after the crews were removed – since 2014, with some blown up in spectacular public displays.
The practice was suspended for several months, but Indonesian fisheries minister Susi Pudjiastuti announced on Monday that it would resume this weekend.
"On the 4th (of May) we will be sinking 51 boats, mostly from Vietnam!"
She did not say if it was in retaliation for the latest diplomatic clash with Vietnam.
Two years ago, Indonesia changed the name of the southern part of the South China Sea to the North Natuna Sea in a bid to show its sovereignty.
More recently, it inaugurated a new military base in the chain of several hundred small islands to beef up its border defence.
The moves have prompted criticism from Beijing whose claims in the sea overlap Indonesia's around the remote Natuna Islands. – AFP