Alarming images have emerged of what appear to be fishermen being shot dead at sea.

ONE News was alerted to the video this afternoon. It's yet to be verified but an online posting of the video says the victims were Fijian and the pictures taken outside Fijian waters.

ONE News has had specialists poring over the video and translating orders apparently given by foreign fishing crews.

Two men are seen clinging to wreckage, desperately trying to avoid a spray of gunfire. Both end up dead in the water.

Five minutes earlier on the video posted on YouTube, there are three fishing boats, one confirmed as a Taiwanese longliner. They appear to be chasing another boat and heavy fire is clearly heard.

An interpreter has revealed to ONE News that one crew member says in Vietnamese: "If you see anyone, just kill."

On the loudspeaker, a voice can also be heard yelling: "Look ahead there, one and two."

Soon after, the men are seen floating in the water clinging to debris.

The YouTube posting claims the pair are Fijian fishermen, situated just outside Fijian waters but ONE News can't yet verify this information.

A third man is shown trying to swim away from the gunfire, but he fails.

The footage also shows a total of four bodies in the water.

But our translator also interprets a Vietnamese voice saying: "One more man, this is the fifth man."

Police hunt uploader of video

ONE News Pacific correspondent Barbara Dreaver has learned Fijian police are now investigating the video.

"The Fiji police are very interested in this video and they are currently looking for the person in the Suva area who uploaded it today," Dreaver says.

She says her Fijian sources, including the police, have told her it does appear that the men in the water are Fijian.

"However, I have to stress this has yet to be verified. And nor to we know exactly when this video was taken," Dreaver says.

She says there has recently been "the odd incident" arising from tension over fishing around Fiji.

For example, a Fijian was found floating in the water by a passing boat and he claimed to have been set adrift by a foreign fishing vessel he was working on.

There is also tension between local fishing companies and foreign fishing companies as the tuna stocks in the region are very short, she says.