Eight Guineans have been arrested by Sierra Leone for an act of piracy against locally-licensed Chinese fishermen inside Sierra Leonean waters.
The Guinean authorities say the men, including several officials, were on a legitimate fisheries protection patrol.
Sierra Leone naval officers say they interrupted an armed hold-up involving two speedboats crewed by armed men 18 nautical miles off Freetown.
They seized one speedboat and said the other escaped towards Guinea.
Daniel Mansaray, commander of the Sierra Leone Armed Forces Maritime Wing, told Reuters news agency that the arrested men were all "Guinean pirates", armed with AK-47 automatic rifles.
He said they included two fisheries inspectors, a naval lieutenant and an army lieutenant from the Guinean armed forces and that they were caught in possession of bags of fish taken off the Sierra Leone-licensed vessels.
Navy sub-lieutenant Joseph Samura told the French news agency AFP that the Guineans were trying to steal the two fishing vessels, which he described as locally-licensed Chinese ships.
"We searched their boat and found two rifles and a quantity of magazines, fully loaded," he said.
A spokesman for Guinea's navy denied the men were pirates and said they were fisheries officers accompanied by military personnel on an official patrol.
But he had no explanation for what the Guineans were doing within Sierra Leone's waters.
A British Royal Navy adviser to the Sierra Leone armed forces, Sean Brady, said "There was one boat with the pirates and one boat to take away all the bounty to Conakry."
He told Reuters: "It is embarrassing for Guinea."
Sierra Leone's newly-elected President Ernest Bai Koroma briefly visited Conakry on Friday - his first foreign trip as head of state.
Mr Koroma had asked Guinean President Lansana Conte for more cooperation on security, said officials.