Tigers on the loose near Dutch village

Two tigers escaped from a big cat shelter near a small Dutch village on Saturday and remained free after a tranquiliser dart fired by police failed to take effect.

The two - Benghal tigers named Radjah and Dehli - remained on the shelter's land, although the fences were reported to be too weak to contain them. Residents in the nearby northern village of Oldeberkoop, population 1,500, were warned to stay indoors.

"Tigers in sight," police tweeted after launching a search with a helicopter and a veterinarian with a tranquiliser gun. "We are now going to try to bring them back to the shelter."

They later said one of the two had been shot with a tranquiliser dart, but that it had not taken effect. "Still trying to tranquilise the animals," they added.

They tweeted an aerial shot of one of the tigers roaming the shelter's wooded terrain.

Oldeberkoop is home to the Felida centre, which receives big cats from circuses and zoos, treats them, and works to replace some in a larger shelter in South Africa.

The pair were rescued from a zoo in north Germany whose owner could no longer afford to feed them.

Dutch media reported that the two tigers appeared to have escaped from their enclosure through a gate that had accidentally been left open.

According to the centre's website, its residents include two lions, eight tigers, a black jaguar, and a leopard.