Hospital bosses answering questions about the Prime Minister not covering his face during an official visit have said that infection control measures state visitors should wear masks.

Boris Johnson visited Hexham General Hospital in Northumberland on Monday morning – hours before MPs debated parliamentary standards.

Photographs showed him meeting masked nurses at the hospital, talking to them and bumping elbows with them, despite not having his face covered.

Soon after that photo opportunity, the Prime Minister put on a mask, which had been handed to him by an aide.

He was not wearing a face covering when he was interviewed on television, with the agreement of those in the room.

Bosses at Northumbria Healthcare NHS Foundation Trust have now responded to members of the public asking why Mr Johnson was not wearing a mask.

They said: “In response to your communication about the coverage you have seen of the Prime Minister pictured without wearing a face mask at Hexham General Hospital, the Trust would like to assure you that infection prevention and control has always been and continues to be of utmost priority in all of our hospitals and in all other Trust sites.

“Our mask-wearing rules are very clear, and it is important to note that everyone that was part of the official visit to Hexham General Hospital on Monday 8 November were formally advised and reminded of these rules on the day.

“Information was included in the written programme.

“These rules include information about mask-wearing and other infection prevention and control measures, such as hand-washing, tucking away loose clothing (ties), and having rolled-up sleeves.

“After the Prime Minister left a welcome meeting, he walked along a mezzanine corridor, for a very short period of time, without a mask.

“This brief moment was captured on camera.

“As soon as this was identified he was given a mask and he put it on.

“The Prime Minister did wear a mask for the majority of the visit.

“He didn’t have a mask on when he did his media interviews, but this was with agreement with everyone else in the room, who did wear a mask.

“We ask that everyone visiting our hospital sites continue to follow our infection control and prevention rules.

“We hope this helps to clarify the situation and we apologise for any upset this has caused.”

On Tuesday, Deputy Prime Minister Dominic Raab said Mr Johnson had followed “all the protocols and procedures” while he was on the premises.