Three people were injured after a mystery white substance in an envelope was delivered to a London restaurant involved in the London Bridge terror attacks.

The substance, described by police as “naturally occurring,” was sent to Feng Sushi restaurant in Borough Market.

The property was evacuated as a precaution and cordoned off by police.

Police were called to reports of an unidentified substance being delivered in an envelope to a restaurant credit: Paul Dawson / @poleydee

London Fire Brigade said firefighters using protective equipment entered the building after they were called to assist police with a "chemical incident" shortly before 2pm.

Forensics experts wearing masks were later seen carrying two brown, padded Jiffy envelopes out of the restaurant in sealed bags.

A Metropolitan Police spokesman said it was not being treated as a terror-related incident.

Three people were treated at the scene for minor injuries as the result of an irritant but did not require hospital treatment.

A member of staff said the envelope had been "addressed to the restaurant, no one in particular".

The restaurant was evacuated as a precaution and was cordoned off credit: Paul Dawson / @poleydee

Paul Dawson, a local businessman, said he arrived at Feng Sushi just after the police.

"The manager was flustered and said 'sorry, we've had something quite bad happen, we have to close,’” he said.

"A community warden then told me that a white powder had been received.”

The police said they were called to "reports of an unidentified substance being delivered in an envelope" to a business in south east London.

Police said no arrests had been made and enquiries continued.

Alex Nypels, 23, a supervisor at Feng Sushi, came face to face with one of the three London Bridge terrorists when they killed eight people on June 3.

Mr Nypels, from Belgium, said one of the attackers, dressed in a red hooded sweatshirt, ran up to him as he stood at the glass door locking up.

“He was right in front of me with only the glass of the door between us," he said.

"He came with a big knife, about 20cm, which had blood on the blade. He was saying, ‘This is for Allah’, and tapped it on the window.”