Dutch police say there have been almost 250 attacks on private homes and business premises using explosives so far this year, more than in the whole of 2022, broadcaster NOS said on Sunday.

Most have taken place in Rotterdam and Amsterdam but there have been others in different parts of the country, from Limburg to Groningen, the figures from the national police coordination team show.

The attacks are mainly linked to the drugs trade but blackmail often has a role as well, NOS said. The 72 perpetrators who have been arrested so far are often young. Two-thirds are under the age of 23 and several have been minors, the youngest being just 14 and 15.

The bombers are also using more powerful explosives and hand grenades left outside a door are giving way to homemade firework bombs which cause a large amount of damage, NOS said.

“We would appear to be stepping up the level of violence and that is worrying,” a police spokesman told NOS.