Russia’s foreign ministry has expressed regret after a Dutch diplomat was beaten up in Moscow – with the attackers scrawling the letters “LGBT” on a mirror.

Onno Elderenbosch was tied up, beaten and the suspects then daubed a heart on a mirror in pink lipstick with the letters “LGBT”.

The Dutch foreign ministry summoned Russia’s ambassador to explain after the diplomat was attacked in his flat.

The motive for the attack is not clear – although referencing the LGBT community suggests the suspects were trying to make a political point as part of their wider actions.

In stark contrast to Russia, where LGBT rights have been on the decline in recent years, the Netherlands is one of the world’s progressive countries when it comes to LGBT equality.

On 1 April 2001 it became the first country in the world to legalise equal marriage. Same-sex sexual activity has been legal since 1811.

The incident comes amid rising tensions between the two countries.

Russia last week protested about the arrest of one of its diplomats in the Netherlands, and the Dutch have complained about Russia’s detention of a Dutch-flagged Greenpeace ship.

Expressing its regret, Russia’s foreign ministry said police in Moscow were taking every measure to find and apprehend the culprits.

Last week Dutch police entered the home of a Russian diplomat in The Hague and took him into custody, after neighbours reported hearing a row inside.

The Dutch foreign minister later apologised for breaking the rules of the Vienna Convention that recognise diplomatic immunity.