A French reconnaissance plane crashed in a ball of flames at Malta's international airport on Monday, killing all five people on board.
The plane plummeted into the ground shortly after take-off, reported Agence France-Presse, killing the five French nationals on board.
The Maltese government said in a statement that there was no indication of an explosion prior to the crash but did not rule out sabotage, saying an investigation was under way into possible causes.
The French defense ministry said the plane had been working on its behalf, carrying out "reconnaissance missions in the Mediterranean".
Three of those who died were employees of the defense ministry, the two others worked for the company which flew the plane, the ministry said.
The Maltese government, which had described those on board as working for a French "customs" operation, said the aircraft was a Fairchild Metroliner Mark III registered in the United States and leased to a Luxembourg company, CAE aviation.
It took off around 7:20 a.m. local time. Shortly afterwards it was seen plunging nose-first towards the ground and exploding into a ball of flames.
"Official information, footage and eyewitnesses, including three members of the Armed Forces of Malta at the nearby barracks, and two commercial airline pilots, clearly indicate that there was no explosion prior to impact," a government statement said.
Remains of all five victims had been recovered and an investigation had begun, it added.
"The flight was part of a French customs surveillance operation which has been taking place for the past five months, with the aim of tracing routes of illicit trafficking of all sorts, including human and drug trafficking amongst others," the government said.
"The flight was registered with the Malta Air Traffic Services as a local flight and was to return to Malta within hours without landing in third countries."
Located just 220 miles north of Tripoli, Malta is on the frontline of Europe's efforts to contain the waves of migrants trying to reach Italy from Libya in boats operated by people smugglers who are often also involved in illicit drugs and arms dealing.
The island is also strategically located for Western powers seeking to monitor developments in conflict-wracked Libya, where a fledgling national unity government is struggling to impose its authority and militants loyal to the Islamic State group have established a foothold.