Lars Vilks, the Swedish cartoonist understood to have been a primary target of one of last weekend’s deadly Copenhagen shootings, has rounded on Danish police, whom he claimed had vastly underestimated the terror threat posed to the city.

A "suspicious" letter has been found outside a café in Copenhagen, the scene of an attack during a free speech event on Saturday.

The slain gunman behind two deadly shooting attacks in Copenhagen was released from jail just two weeks ago and might have become radicalized there last summer, a source close to the Danish terror investigation said.