The number of high-rise apartment blocks wrapped in combustible Grenfell Tower-style cladding has soared to 470 after councils identified an extra 156 towers in the private sector using materials similar those that spread the fire which claimed 72 lives.

The government made the admission on Thursday and revealed that the number was expected to rise further because the cladding status of another 170 private sector residential buildings is still to be confirmed.

It said that only 19 buildings higher than 18 metres (60ft) – including affordable and private blocks – have so far had their dangerous cladding replaced, leaving tens of thousands of people living in homes wrapped in flammable materials.

More than a year since the disaster, only four of the 297 private buildings have been fully repaired and only 17 others have repairs under way. Fears over the cladding causing a second blaze rose on Thursday morning in Manchester when there was a fire in a block next door to one wrapped in combustible materials.

Katie Kelly, a resident of Vallea Court, wrote an open letter to the freehold owner saying: “We are pleading with you to speed this up and commit to removing the cladding... We fear that our lives are in genuine danger... people could very likely lose their lives over this.”

A leading member of the survivors’ group Grenfell United, Ed Daffarn, warned that “Grenfell two is in the post” unless urgent action is taken to remove combustible cladding

Already, 159 council and social housing blocks had been identified as containing combustible cladding. The government has pledged to take £400m from the current affordable housing budget to help fund repairs.

Progress on private buildings is proving slower because some freeholders are arguing that leaseholders should foot the bill. Ministers have insisted freeholders should pay, but have no enforcement powers.

Announcing the figures, the housing secretary, James Brokenshire, said: “Fire and rescue services are working with building owners to ensure residents are safe now. But I want to see swifter progress in removing unsafe cladding.

“I have been clear that leaseholders should be protected from unfair costs and we expect the industry to do the right thing. If they don’t, I will continue to explore other routes and I am not ruling anything out.”

Labour attacked the government’s handling of the crisis. John Healey, the shadow housing secretary, said: “The same pattern of institutional inaction and negligence that led to the Grenfell Tower fire has typified the government’s response since.

“Ministers have been off the pace at every stage and they’re still not doing enough to ensure people are safe. Ministers must now set a deadline to make all blocks safe and take all steps necessary to see the work is done.”

Grenfell-style cladding: what's wrong with the system and what happens now? Read more

Ministers are planning to launch a taskforce to help councils identify the type of cladding in use on private tower blocks higher than 18 metres amid growing concern thatofficials still do not know, more than a year since the Grenfell Tower disaster.

The Ministry of Housing, Communities and Local Government ordered councils to identify all private high-rise residential buildings with aluminium composite cladding by the end of May. That has led to the identification of the extra 156 private sector blocks over 18 metres high.

Ministers have voiced frustration that private landlords have not come forward in sufficient numbers to declare whether their buildings are clad in combustible materials that have failed fire tests.