The Dutch government expelled two alleged Russian spies this year after they were accused of planning to hack into a Swiss chemicals laboratory where novichok nerve agent samples from the Salisbury attack were analysed, it has emerged.

The men were arrested in The Hague as part of an operation involving British, Swiss and Dutch intelligence agencies. The Swiss daily newspaper Tages-Anzeiger reported that the men were carrying equipment that could be used to break into the Spiez laboratory's IT network when they were seized.