Dutch police have arrested a politician, Mr van Doorn, the leader of The Hague Unity Party, on suspicion of involvement in a plot to assassinate Prime Minister Mark Rutte. The prime minister's security service said Arnoud van Doorn was arrested on Sunday. This was reported by the BBC news agency.
According to the prime minister's security service Mr van Doorn "displayed suspicious behavior" as he walked through the same area of the city as Mr Rutte. Mr van Doorn was released on Monday after police interrogation, the service said.
However, van Doorn's lawyer Anis Boumanjal said he should not have been arrested because there was no reasonable suspicion of guilt.
The arrest was reported on Tuesday, a day after Dutch media said Mr Rutte had been given extra security over fears that he may be the target of an attack or kidnapping by a criminal gang.
Mr Rutte, 54, has been followed by so-called spotters linked to a drug trafficking gang, the De Telegraaf newspaper reported on Monday.
Telegraaf journalist Mick van Wely told broadcaster NOS the matter was being taken "very seriously". NOS confirmed the report but Dutch security authorities and the prime minister declined to comment.
Outside parliament on Monday, as he arrived for coalition talks, Mr Rutte told journalists, "Safety and protection are issues never to be discussed in public."
The Dutch security authorities and prime minister themselves refused to comment on the situation.
Prosecutors in The Hague confirmed the arrest of Mr van Doorn to Dutch media and said an investigation was still ongoing.
A spokesperson said there was suspicion that Mr van Doorn was trying to gather information for "preparation of attempted murder". No further details were provided.
Prior to his arrest, Mr van Doorn had been in the Hague for about an hour, his lawyer said. He said Mr van Doorn had a coffee at a cafe and made some inquiries at a fitness center before walking past a BMW thought to be chauffeuring Mr Rutte.
"They weren't reasonable in how they handled the case. It was very dramatic," Mr Boumanjal said. "They detained him for 30 hours."
According to counsel, the arrest was an excessive reaction to recent concerns about the security of the prime minister.
The reported threat to Mr Rutte follows the murder of prominent Dutch journalist Peter R de Vries, who was known for investigating the criminal underworld in the Netherlands.