White lights filmed near Chile volcano puzzle internet users

Footage of two mysterious white lights hovering near Chile's erupting Calbuco volcano has tens of thousands of internet users speculating about the source of the unexplained phenomenon.

Yesterday the Calbuco erupted for the first time in half a century, spewing a giant funnel of ash high into the sky near the southern port city of Puerto Montt and triggering a red alert.

As hundreds of people filmed the enormous plume of ash and smoke rising from the mouth of the volcano some captured a so-far unidentified object that has sparked a number of theories.

Some internet users said the pair of lights that hovered near the plume before disappearing were either police helicopters, an optical illusion or a UFO.

"Some believe it may be a drone or a helicopter of the police," wrote YouTube user Ana Luisa Cid, who posted a compilation of footage of the object.

"What is striking, in my opinion, is that the object remained static, then vanished. Optical illusion?"

Authorities have declared a state of emergency, sent in the army and evacuated a 21km radius around the volcano after the twin eruptions.

There were no immediate reports of injuries. A 21-year-old mountain climber was initially reported missing, but later turned up alive.