The Tories risk regaining their reputation as the “nasty party” if they end the £20-a-week rise in Universal Credit, the Government’s former homelessness adviser has warned.

Dame Louise Casey said that if the increase is withdrawn at the end of March as planned it would be “too punitive” for families struggling during the coronavirus pandemic.

Her warning comes as Chancellor Rishi Sunak is under growing pressure from Conservative MPs to extend the increase – originally intended as a temporary measure following the outbreak last year.

They include a number of the so-called “red wall” Tories who captured a series of Labour strongholds in the North and Midlands as Boris Johnson swept to victory in the 2019 general election.

They have argued that with lockdown restrictions required for far longer than was originally envisaged, people need continuing support while the economy begins to recover.

On Monday, six Conservative MPs defied the party whips to vote for a symbolic Labour motion calling for the increase to be retained.

Mr Sunak, however, is reported to be deeply reluctant as he seeks to begin to repair the damage caused to the public finances by the pandemic.

In a BBC interview, Dame Louise said that while she understood his reluctance to say his “chequebook is forever open”, he needed to consider the effect it would have on people’s lives.

‘‘The Treasury need to step back and not feel this constant responsibility to close the books all the time and fight and fight and fight,” she said.

“They need to step back and think if we really want to rebuild Britain, what type of economic policy do we need to put in place that will … not take the knees out from under people.

“To remove that £20 a week – it’s too punitive, it’s not the right thing to do, and I think they just go back to being the nasty party.”

Dame Louise said the country had been “torn to shreds” by the pandemic and called on ministers to draw up plans to deal with the fallout.

“The wounds it’s inflicted on the country are far deeper and greater than anything I’ve ever seen in my lifetime in terms of ordinary folk having to claim Universal Credit, ordinary people having to turn to food banks, ordinary people becoming homeless,” she said.

“I think we will need to have a big plan to deal with the wounds inflicted by this pandemic once everybody’s vaccinated.

“And I think the Government needs to turn its attention to that now, and not leave it until the summer.”