Schools are due to be given more guidance on how to keep staff and pupils who are still attending classes safe and healthy during the coronavirus outbreak.

Union leaders have been calling for clear advice on issues such as social distancing in schools and whether there is a need for personal protective equipment (PPE) such as masks.

It is understood that new guidance covering health and safety issues is being prepared.

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Schools in England officially closed on Friday, but have remained open for vulnerable pupils and the children of key workers, such as medics, police and delivery drivers.

Early indications suggest the numbers of pupils arriving at schools is lower than first expected by school leaders, as parents heed advice to keep children at home unless they have no other option.

Downing Street said attendance at schools in England was around 10 per cent of normal levels on Monday.

But there were concerns among school and teachers’ leaders about a lack of clarity on how to keep those children and staff who are still at school protected from Covid-19.

Teachers’ leaders took part in a telephone meeting with education secretary Gavin Williamson this afternoon.

Mary Bousted, joint general secretary of the NEU teaching union said afterwards that the secretary of state had listened to concerns.

“He was really understanding of the concerns that we were raising about vulnerable members of staff in schools and about the safety of children, teachers, support staff and leaders,” she said.

“Further guidance is being produced for keeping schools as safe as possible so that there is as little spread of infection in schools as can be.”

She added that Mr Williamson said he was “proud” of the work teachers and school leaders are doing to support children.

The NAHT school leaders’ union warned earlier that fewer school staff may be “willing or able” to work following the prime minister’s move to lock down Britain in the absence of clear advice on safety.

In a message to members, NAHT general secretary Paul Whiteman said: “Having heard the prime minister speak, many colleagues will be rightly concerned for loved ones and understandably anxious about the personal risk of simply going to work.

“It would not be surprising to find, in the absence of clear government advice on keeping safe, that fewer colleagues are willing or able to work today than yesterday.

“It is absolutely vital that we have sight of the expert medical evidence on safe levels of attendance and density, and are provided with practical advice on the protective steps we should be taking in schools.

“From masks or other PPE, to distancing children from each other, to sufficient supplies of soap and hand sanitiser, schools urgently need answers to their questions about effective safety measures.”

A government spokesman said: “We are closely monitoring the situation and will continue to work with local authorities to ensure schools and colleges get the help and support they need over the challenging weeks and months ahead.

“We are urging people to do everything they can to stay at home, protect the NHS and save lives.”