The man who set fire to the British embassy in The Hague in April has been jailed for 30 months, 10 suspended, and ordered to undergo psychiatric treatment on his release.

Alexander B, who is 30, was a driver and security guard at the embassy but became addicted to drink and drugs and felt he was being bullied at work, RTL news reports.

According to the broadcaster, the night before the fire B had drunk a large quantity of beer and worked out a plan to dump the ambassador – whom he was due to drive to Belgium that day – out of his car with no clothes on.

Instead, he used turpentine and a lighter to set fire to the rooms used by the ambassador and his deputy. He was found by emergency service workers watching the fire in the embassy courtyard and was arrested.

When his home was searched, police officers found a number of weapons, including a gas gun, several knives, a cosh and knuckledusters.

B told the court during the August hearings he had no idea what had come over him and was extremely sorry for his actions.

No one was injured in the fire but there was considerable smoke and water damage. The British embassy is housed on the Lange Voorhout in the diplomatic quarter of The Hague.