Foreign diplomats who continue to gather Dutch traffic fines will face sanctions including a voluntary fine from May 1, foreign minister Stef Blok has confirmed.

The Netherlands stopped issuing fines for speeding and parking without a ticket to diplomats in 2015, after a court said this broke the Vienna treaty on diplomatic immunity.

However, from May 1, the foreign ministry will write to the diplomat concerned, informing them that they have broken traffic laws and asking them to make a payment equivalent to the actual fine, the foreign ministry said.

In addition if an embassy or international organisation is responsible for a ‘disproportionate’ number of offences, the foreign ministry will speak to the staff and ‘take further measures’ if necessary.

These could include naming the worst offenders and cutting back on perks, Blok said.

The number of traffic offences involving cars with CD plates has gone up sharply since the threat of a fine was removed, the justice ministry said.

In 2015, 9,850 cars with CD plates were caught on speed cameras, but by last year the total had reached nearly 30,000.