The head of a division in Belgium’s equivalent of M16 is suspected of passing secrets to a Serbian agent posing a threat to the EU

A senior Belgian counterintelligence officer is under house arrest after allegations that he spied for Russia in a case that could highlight the security threat to Nato and European Union headquarters in Brussels.

The major, head of a division in Belgium’s external security department of the General Intelligence and Security Service (Giss), the equivalent of MI6, is suspected of passing secrets to Russia via a Serbian agent.

In a further blow, Clement Vandenborre, the head of counterintelligence in Giss, has been removed from office pending an investigation into allegations he illegally destroyed documents.

The turmoil at the top of Belgium’s counterintelligence services raises concerns that the security of key international institutions, including the western military alliance, have been compromised.

The unnamed major is suspected of