The tiny Pacific nation of Palau says it hopes to use drone patrols to deter illegal fishermen from using its vast territorial waters in what officials believe is a world-first use for the technology.

Palau has an exclusive economic zone (EEZ) of 630,000 square kilometres (240,000 square miles) -- roughly the size of France -- but only one patrol boat, making it a prime target for illegal trawlers.

A five-day test programme using three unmanned aerial vehicles (UAVs) -- officials prefer the term because "drone" is felt to have military connotations -- wrapped up on Friday after impressing locals.

President Tommy Remengesau said the UAVs showed potential to "greatly increase the efficiency of our surveillance capability and, most importantly, significantly decrease the overall cost of the joint surveillance effort".

The idea of using the drones emerged after Australian mining magnate Andrew Forrest visited Palau in January and asked his Minderoo philanthropic foundation to examine the illegal fishing issue.

"Andrew absolutely loves the pristine environment of Palau and also loves the people there," Greg Parker of the Minderoo Foundation said.

"He wasn't going to stand back and watch Palau being bullied by illegal fishermen."

The foundation paid for the trial and Parker said the data gathered would be analysed to see if UAV patrols were feasible, with a 12-month trial the next step if they get a green light.

He said experts in the field were not aware of UAVs being used for long-range maritime patrols before and other countries in Micronesia had already expressed interest in adopting similar measures.

He said in addition to patrols, UAVs could also be used for purposes such as search and rescue, mapping and surveying marine wildlife.

Palau is already regarded as a leader in marine conservation after creating the world's first shark sanctuary in 2009.

Earlier this year, Remengesau also proposed banning all commercial fishing from its waters, saying the nation of 21,000 people generated negligible revenue from the industry and preferred to concentrate on attracting tourists.