A gunman who stormed into the headquarters of Dutch national broadcaster NOS demanding airtime today claimed to be from a "hackers' collective", according to a reporter who spoke to him.

NOS was off air for around an hour. When it came back, it showed recorded footage of the young man, wearing a black suit, white shirt and black tie, and carrying a pistol.

Speaking calmly to a man off-camera, the intruder said: "We are hired in by intelligence agencies."

Shortly afterwards, police arrived with their guns drawn and ordered the man to drop his weapon and put his hands up. At least five police officers then ordered him to turn around and lie down, which he did and he was arrested without a struggle.

Police said in a statement that the man demanded airtime and threatened that bombs would go off at several locations around the Netherlands if his demand was not met. Special police units were searching the building in Hilversum, about 20km east of Amsterdam..

There was no immediate indication that the incident was related to Islamic extremism. Nobody was injured and there were no reports of shots being fired.

NOS reporter Martijn Bink said he spoke to the man after he was arrested and he claimed to be from a hackers' collective. He did not elaborate.

The broadcaster later reported on its website that the man had a silencer on the pistol and threatened a security guard, forcing him to take him upstairs to the editorial offices.

When the incident was over, NOS director Jan de Jong told the broadcaster that the headquarters had beefed up security in the aftermath of the attack on satirical newspaper Charlie Hebdo in Paris in which 12 people were killed.

The media park in Hilversum, home to many Dutch broadcasters, has been tightly guarded for years, since populist Dutch politician Pim Fortuyn was gunned down in a car park there in 2002.

While the broadcaster was off air, a screen on the NOS1 channel read "Please be patient" in Dutch.

All staff were evacuated from the building as the situation unfolded and remained outside nearly two hours later as police searched the building. NOS resumed broadcasting from a studio in The Hague.

Staff at NOS led the man into a studio near the one where the 8pm news was to have been broadcast live. In the studio, he spoke to the security guard he had forced to take him into the offices. He never appeared live on television.