A Taiwan-flagged boat has been caught with an illegal haul of more than 100 shark fins and is being escorted back to a home port, Taiwanese authorities said.

Five shark carcasses and 110 shark fins were found on the vessel in an "obvious violation of shark finning", Taiwan's Fisheries Agency said in a statement late Friday.

The boat was carrying over 10 tons of fish, including yellow fin tuna, an amount "significantly discrepant" to that recorded in the vessel's logbooks, the agency said.

The boat was being escorted back to a home port by a Taiwan patrol vessel for further investigation.

Environmental activist group Greenpeace earlier this month boarded the boatl, accusing her crew of operating illegally near Papua New Guinea.

The group said it it found sacks of shark fins from at least 42 shark carcasses though only three had been recorded in the boat's logs.

At the time, Taiwan's Fisheries Agency rebuked Greenpeace for boarding a vessel without permission from the government, countering that the boat was licensed.

Under both Taiwanese law and Pacific fishing rules shark fins cannot make up more than 5 percent of the weight of sharks caught, according to Greenpeace.

A lucrative black market trade in shark fins flourishes in Asia with poaching vessels plying waters beyond national jurisdictions often escaping authorities' efforts to clamp down on illegal fishing.