The Commons Speaker, Sir Lindsay Hoyle, is facing calls to urge MPs to wear masks in the chamber, after cabinet ministers and many Tory backbenchers shunned the advice during a packed eight-hour debate on Afghanistan. Although face coverings stopped being mandatory in most settings on 19 July, government guidance that face coverings should be work in “crowded and enclosed spaces” remains in place, and rules set down by the parliamentary authorities say they should be worn in the main debating space. Four trade unions representing parliamentary staffers wrote to Hoyle on Thursday raising concerns that the scenes of unmasked politicians sitting shoulder to shoulder on the green benches represented “the starkest example yet of the unwillingness of a significant number of MPs to take the most basic of precautionary measures to help protect staff”. They said the “dismissiveness” was insulting and also claimed there was confusion about who was responsible for “ensuring a safe working environment in parliament”, after Boris Johnson’s spokesperson said questions about the rules on masks in the Commons and Lords were “a matter for the parliamentary authorities”. The Guardian can reveal there has been an “uptick” in Covid cases among security workers around the estate in the previous two weeks. As a result, new guidance was issued the day after parliament returned for its one-day recall, telling security staff they must get tested by Saturday at the latest. They have also been told to wear a face covering at all times unless exempt and to maintain social distancing, despite the legal 2-metre requirement also being dropped last month. The general secretary of the Prospect union, Mike Clancy, said it was “deliberately misleading and outrageous” of Johnson’s spokesperson to suggest it was up to parliamentary authorities to mandate mask use, instead of it being up to individual MPs to show personal responsibility. He said: “The Speaker has made it abundantly clear that he expects MPs to wear masks, and Prospect has written to all MPs asking them to take this basic step to protect staff, a step that the PM himself described as ‘simple courtesy’ only last month. “Unions will not stand by while staff are put at risk by reckless politicians, and following this shameful episode we are once again asking the Speaker to take a tougher line with MPs when parliament returns next month.” There were some notable exceptions among the vast swaths of Tory backbenchers who chose not to wear masks. Those who did have face coverings on included the former prime minister Theresa May and the health select committee chair, Jeremy Hunt. A Commons spokesperson said: “Our priority is to ensure a safe and functioning parliament in line with government regulations. Passholders should continue to exercise caution when they are on the estate and we will, of course, monitor the situation from day to day.”