The Hague, Netherlands: The creepy clown phenomenon, which has been spooking the United States, appears to have arrived in the Netherlands after sightings of two people dressed in masks and bearing weapons, Dutch police said.

One person was seen overnight on Monday armed with a knife and a hammer, dressed in a costume and a scary clown mask near a park in the southern town of Oss.

And another was seen on Tuesday, after being spotted earlier in the week by residents in Almere, close to Amsterdam, further north in the country.

"Dear killer clown from Oss, clearly you find it either pleasant or fun to give people the fright of their lives," police in Oss wrote Tuesday on their Facebook page.

"You probably don't know, but to play clown in this way is punishable," they warned, adding they were taking the matter very seriously.

Almere police added these "possible pranks seem to have become a trend in the Netherlands now."

Creepy clown sightings in more than a dozen US states in past weeks have caused a wave of hysteria, forcing police and schools to scramble to contain spreading jitters.

Even the White House weighed in, warning that local law enforcement authorities were taking it seriously in the run-up to Halloween.

British police forces have also been called to several incidents around the country involving pranksters dressed as clowns jumping out and trying to frighten people.