A Conservative MP has branded mask wearing "mumbo-jumbo” during a debate in the House of Commons.
Sir Desmond Swayne, Tory MP for New Forest West, questioned the efficacy of face coverings to prevent the spread of Covid.
His remarks came as the health secretary made a speech outlining the government's new measures to try and contain the spread of the Omicron variant.
Face coverings will be compulsory on public transport and in shops in England from Tuesday.
Addressing Sajid Javid, Swayne said: “Over the last few months, there’s been a useful control experiment on face coverings given the different policies pursued in Scotland and England.
“What estimate has he made of the result? It’s mumbo-jumbo, isn’t it?”
Unlike England, mask wearing has been mandatory in Scotland since the beginning of the pandemic.
Since measures were lifted in England, Scotland has reported some of the highest Covid case numbers in the UK.
Evidence published by the UK Health Security Agency (UKHSA) shows that face coverings are, to a certain extent, effective at reducing Covid transmission in healthcare and community settings.
The health secretary responded to Swayne by pointing out that experts advising the UK continue to recommend the use of face coverings.
“I think if my right honourable friend is suggesting that there are mixed views on the efficacy of face coverings in helping to fight this pandemic, he would be right,” said Javid.
“But I would point him to work that’s already set out by the UKHSA.
"I think it was published, if I remember correctly, last month where they refer to the number of reports where they set out in certain settings where face coverings can help.”
A handful of backbench Tories appeared without face coverings in the Commons chamber, with one openly shouting his opposition to pleas from Labour MPs to put one on.
Shadow health minister Rosena Allin-Khan told Javid that Labour supported the government’s decision to reintroduce mask wearing, and that “it should never have been abandoned in the first place”.
She added: “And can I ask the Secretary of State when Conservative backbenchers will start wearing their masks?”
Labour MP for Hove, Peter Kyle, could be heard shouting at the unmasked Tory MPs to “put it on” – with Conservative MP Alec Shelbrooke, responding with: “No.”
The exchanges came after the government announced the public would be required to wear masks on public transport and in shops again in light of the emergence of the new variant.
New guidance has also been provided to schools, which have been advised that secondary school pupils should wear masks.
Mask wearing ceased to be mandatory in July on “Freedom Day” in England when the government relaxed most coronavirus restrictions.
The topic of masks within the Conservative party itself continues to be a source of debate.
In October, Jacob Rees Mogg suggested that the “convivial fraternal spirit” of Conservative MPs meant that they did not need to wear masks in the House of Commons.
Earlier this month, Boris Johnson was criticised for temporarily appearing in a hospital in Northumbria without wearing a mask.
While Downing Street and the Northumbria NHS Trust defended him, he later admitted to a select committee he should have worn one for the entirety of the visit.