The incident occurred on Tuesday at the Zeebrugge naval base, where the exhaust system of the Oostende, a mine hunter, overheated and was releasing smoke, according to the Belgian ministry of defence.

"Technical investigations are underway and all hypotheses are being considered," a spokeswoman for the Belgian federal prosecutor's office told AFP.

Although there was no fire and no one was injured, firefighters were called to the scene to cool down the equipment, said the defence ministry, which is also investigating.

Responding to lawmakers' questions on Wednesday, Defence Minister Theo Francken compared the case to the alleged attempted sabotage of German naval vessels in Hamburg.

"We have already seen this in Germany, where acts of sabotage were involved," Francken said, describing the Belgian incident as "striking".

A Greek and a Romanian man were arrested this week on suspicion of having tried to sabotage German navy corvettes in 2025.

Germany and other NATO members across Europe are on high alert over suspected Russian espionage, drone surveillance and sabotage.