The government could miss its own deadline for cladding removal if no progress is made to speed up the process, the UK’s spending watchdog has said.

In a new reportThe National Audit Office (NAO) said up to 60% of buildings with hazardous cladding had not yet been identified by the government and, at the current rate of progress, would not meet its own estimated completion date of works in 2035.

The report continues the conclusion of the Grenfell inquiry in Septemberwhich found that risks had been ignored and there was “systematic dishonesty” by those who made and sold the cladding involved in the fire in west London in 2017, in which 72 people died.

The government has been contacted for a response.

The report assessed how quickly the Ministry of Housing, Communities and Local Government (MHCLG) was completing work to replace dangerous cladding on tower blocks in England, and aimed to provide an update on a previous NAO report in 2020.

It found there had been “a substantial increase in remediation activity” since then, with 4,771 buildings over 11 meters high included in the government’s remedial works plan up to August.

However, it is estimated that a further 7,200 buildings in England have yet to be identified with this cladding and some “may never have been identified”, the NAO continued.

Progress on replacing the siding was also slow.

Although the MHCLG spent £2.3bn on works on identified buildings, the report said work had only been completed on around a third of them and had not yet started on half.

The government’s suggested end date for completing cladding works on these buildings was 2035, but it was not on track to meet this deadline and “there are significant challenges to overcome”, the report said.

The NAO recommended that if progress in identifying buildings with dangerous cladding did not improve by the end of 2024, the government should consider further measures.

These include mandatory registration for medium-rise buildings – and as with high-rise buildings under the Construction Safety Act of 2022stricter enforcement activities and actions to assist with disputes between residents and building owners.

“Many people still do not know when their buildings will be safe, contributing to residents experiencing significant financial and emotional hardship,” the report says.

The watchdog also highlighted there were problems keeping taxpayer contributions to the works capped at £5.1bn.

The MHCLG estimate for the costs of all the works amounted to £16.6 billion and the NAO said that although the government planned to recover around £3.4 billion from a new Construction Safety TaxThis was not expected to be introduced until fall 2025 at the earliest.

In London, More than £1 billion has been paid to remove dangerous cladding from blocks of flats in the last six years.

The Greater London Authority, which manages the plans on behalf of the government, said 58% had already been fully remediated or were being worked on.

The report’s findings come after Chancellor Rachel Reeves announced in the Budget that the government would invest more than £1bn in repairs to buildings with dangerous cladding in 2025-26, including new investment to accelerate the rehabilitation of social housing.

Gareth Davies, director of the NAO, said: “There is a long way to go before all affected buildings are safe, and the MHCLG must address the risks for its approach to be successful.

“To meet its £5.1bn cap in the long term, MHCLG must ensure it can recover funds through the successful implementation of the proposed building safety levy.”

Sir Geoffrey Clifton-Brown, chairman of the Commons Public Accounts Committee, who previously met Grenfell fire survivors, said: “The program is falling behind and MHCLG needs to pick up the pace to get it back on track.” , and added “the government must take measures to better protect the taxpayer.”

“It urgently needs to ensure its fraud controls work and that developers contribute their fair share to the costs.”