Teachers' unions have denied suggestions by Conservative MPs they have been "actively obstructive" over the reopening of schools in England.
Union leaders said it was important for children to return to school "as quickly as possible" and when "safe to do so".
But MPs accused them of running a political campaign to keep schools closed.
Unions appeared before the Education Select Committee on Wednesday morning.
Tory MP and committee member Jonathan Gullis, who is a former teacher and a former NASUWT union representative, said he was "absolutely outraged at the sheer damage the unions have done to the teaching profession".
He accused the National Education Union (NEU) of running a "political campaign... to basically make sure schools did not open".
Mr Gullis, MP for Stoke-on-Trent North, said five conditions set out by unions for schools to reopen safely had been "effectively five tests".
But Patrick Roach, the general secretary of the NASUWT, rejected this, saying they were conditions the government needed to demonstrate for the safe reopening of schools.
Dr Roach said schools "should be open as soon as possible" and that "some already are to a large degree".
Mary Bousted, joint general secretary of the NEU said: "We'll support a full school reopening when it is safe."
'Breathe fear into parents'
Mr Gullis asked: "Why is it that every time I see a union rep on TV they're saying schools aren't safe to open?
"A campaign has been run, whether you like it or not, to breathe fear into parents about the idea of sending their kids back to school... it has come across to parents that schools are death traps."
Tom Hunt, Tory MP for Ipswich, added: "The perception that many people have in this country, whether rightly or wrongly, and it is a reality, sadly, that many people feel as though some of the teaching unions have actively obstructed the reopening of schools ahead of September."
Robert Halfon, Tory MP for Harlow and chairman of the committee, asked the unions: "Why is it that children and parents can have access to Primark over the next few months, but many of them won't have access to schools according to your risk assessments?"
Union leaders told MPs they wanted children back in school as soon as possible, but they raised concerns about schools leaders' ability to do so in the autumn term under the current social distancing rules.
Social distancing pressures
Dr Bousted said: "The problem we have in England in particular is that we have some of the highest pupil-teacher ratios.
"We've got more pupils in classes and the footprint on the classes is smaller so if you're going to continue with social distancing, it puts the pressure on the school site to be very great."
When asked whether schools will be able to open fully in September under current restrictions, Dr Bousted told MPs: "If the government retains its social distancing rules then they can't.
"So that's why we then need to look at an education recovery plan, which is focused on more than school buildings."
Dr Roach told the cross-party committee of MPs that the issue of reopening schools had to be looked at "in the context of a public health crisis".
"We have a public health crisis which led the government to close schools in the first place and any decisions around the reopening of schools have got to be set in that context."
Dr Bousted said the science surrounding Covid 19 was not negotiable and that it must "lead the process in relation to reopening" of schools.
She said the advice from government had been "woeful", but said the risk assessments the union had produced were based on guidance from the Department for Education.
If committee members had a problem with it, she added, they should "take it up" with the department.
Follow Katherine on Twitter