Andy Burnham has won backing from other northern MPs for his calls for an overhaul of council tax amid concerns constituents in the north of England are paying double the amount paid in a wealthy part of London.

The Greater Manchester Mayor, the favourite to replace Sir Keir Starmer in a potential leadership challenge, has said he wants to reform council tax, branding the current system “highly regressive”.

It comes as a separate analysis by campaign group Fairer Share shows that constituents in Makerfield, where Burnham is standing in a by-election, pay twice as much council tax as residents in Westminster in similar-sized properties.

In his campaign launch, the Manchester Mayor highlighted council tax as being ripe for reform, criticising the fact that the levy is still using property valuations from more than 30 years ago.

Speaking earlier this month, he said: “It’s a highly regressive tax, and I think it’s not justifiable based on those 1991 valuations. I see a big case for land and property and business taxation to be changed.”

His plans are being backed by Labour MPs, who want to see council tax and stamp duty scrapped in favour of a new proportional property tax, which would see homeowners largely in the south pay more in tax than those in the north.

Under a new tax, which would apply a uniform annual levy based on a percentage of the property’s market value, households in areas such as Makerfield could see a saving of around £500 annually compared with council tax.

So far, six Labour backbenchers, Jonathan Hinder, Patrick Hurley, Chris Webb, Ian Byrne, Jonathan Brash and Afzal Khan, have backed changing the council tax in favour of a proportional property tax (PPT).

Jonathan Hinder, MP for Pendle and Clitheroe, said such a change would “reaffirm to ordinary people that Labour’s on their side”.

“Stamp duty and council tax are unpopular and broken, and there’s a credible alternative ready to go. A PPT could redistribute to lower-income and ordinary families within Labour’s fiscal rules. It’s an idea whose time has come,” he said.

His comments were echoed by Jonathan Brash, MP for Hartlepool and chair of the council tax reform APPG, who branded council tax as “broken”.

“It is a poverty tax that hits working people hardest while the wealthy get away lightly,” he said.

“Hartlepool, like Makerfield, shows just how rotten this system has become. Families in ordinary two-bedroom homes are paying more than people living in million-pound mansions in Westminster. That is not fair. It is a national scandal.”

Criticism of the existing council tax system and stamp duty has been growing for some time. Earlier this month, economist Paul Johnson, the former director of the Institute for Fiscal Studies and now provost of The Queen’s College, Oxford, backed a petition to review council tax and stamp duty, saying: “Any government serious about both growth and fairness would have this top of their agenda.”

Andrew Dixon, chair of the Fairer Share campaign group, which advocates for a proportional property tax, said Burnham’s comments had “struck a chord”.

“The UK already has the highest property taxes in the OECD. Replacing an outdated and inherently regressive council tax system will create a fairer system that doesn’t need to increase the overall tax burden. Meanwhile, replacing stamp duty would improve labour mobility, support downsizing and help households move to homes that better suit their needs,” Dixon said.