People in the capital, Kinshasa, stoned and torched the 12ft (3.7m) triangular prism that looked like other metal monoliths that have cropped up around the world over the last few months.

It had begun to draw selfie-takers, which fuelled rumours on social media.

Some feared it was satanic or put there by aliens or by a secret cabal.

“We woke up and saw this metallic triangle… We were surprised because it is a triangle that we often see in documentaries about freemasons or illuminati,” local resident Serge Ifulu is quoted by Reuters as saying.

Speculation over the pillar, which appeared in the Bandal neighbourhood over the weekend, became frenzied by Wednesday.

Witnesses say residents destroyed it to see what was inside – it turned out to be hollow with the metal sheets spread over a frame.

Local mayor Bayllon Gaibene told the BBC that he had now sent some of the material to be tested by scientists to find out about its origins.

He denied an accusation by Kinshasa’s Governor Gentiny Ngobila that he was responsible for the mysterious monolith.

Mr Ngobila’s spokesman had said the mayor had wanted to create a buzz.

It is not the first such metal object to have created a stir of late, especially with science fiction fans.

Tourists rushed to see a metal monolith which appeared in Utah, in the US, in November.

Several have appeared in the UK, including one on the Isle of Wight in December.

That time artist Tom Dunford said he had erected the structure for “fun”.

One that turned up earlier this month near Turkey’s Gobekli Tepe, an ancient temple and World Heritage Site, transpired to be a stunt by the government to promote its new space programme.

The shiny pillars capture the imagination because they are reminiscent of the imposing black monoliths created by an alien species in the science fiction film 2001: A Space Odyssey.