The minister, also burgomaster (mayor) of Kortrijk, addressed Saturday evening the inhabitants of this city of West Flanders who participated in a municipal ball, in a video message broadcast on Sunday by public radio and television RTBF.

Van Quickenborne said he received a phone call Thursday from federal prosecutor Frédéric Van Leeuw. “He warned me of a kidnapping project that was targeting me,” said the minister in this video message, adding that he did not want to cancel the festivities so as not to “give reason to the drug mafia”.

The Belgian federal prosecutor’s office announced on Saturday that the minister had been placed under reinforced police surveillance, and that three suspects had been arrested in the Netherlands. The Dutch public prosecutor’s office specified that they were three men aged 20, 29 and 48, of Dutch nationality.

A fourth suspect was arrested in the Netherlands, a judicial source said on Sunday.

Their transfer to Belgium has been requested.

The judicial source confirmed to AFP that an automatic weapon had been discovered in a vehicle spotted near the minister’s home in Kortrijk.

The Flemish daily Het Laatste Nieuws had reported that firearms including Kalashnikovs, and bottles filled with gasoline had been found in the suspect vehicle, registered in the Netherlands.

The minister reacted on social networks on Saturday, affirming his determination to continue the fight against “organized crime”. “We will never bow to violence,” he said.

Belgian Prime Minister Alexander De Croo denounced a “purely unacceptable threat”. “We won’t be intimidated by anyone,” he tweeted.

The Belgian federal prosecutor’s office explained on Saturday that it had “been informed during the last week of a possible threat” to the Minister of Justice. An investigation, entrusted to an investigating judge, “quickly indicated that this threat should be taken seriously”, he added.

The minister was placed under increased police surveillance and canceled some of his activities. The prosecution declined to provide any further details of the investigation.