Current and former MPs will give evidence at the Grenfell Tower inquiry amid union calls for politicians to be held to account.

Northern Ireland Secretary Brandon Lewis will on Wednesday be the first politician appear as a witness at the inquiry, which is attended by bereaved family members and survivors of the 2017 blaze.

Mr Lewis was a minister with responsibility for fire safety from 2016 to 2017.

Stephen Williams, Lord Wharton and Gavin Barwell, all of whom were ministers with responsibility for building regulations in the run up to the disaster, will also appear, and former fire safety minister Lord Pickles.

Matt Wrack, general secretary of the Fire Brigades Union, called for politicians who supported deregulation in the years leading up to the fire to “bear the brunt of the blame”.

“Politicians over successive decades committed to deregulation as a fundamental political idea,” he said.

“They have scrapped standards, privatised public services and weakened the regime of inspecting buildings.

“A clear line can be drawn from these political decisions to key failures at Grenfell, with highly flammable cladding and insulation facilitated by a lack of clear regulation.”

Mr Wrack added that ministers “imposed the worst cuts in our history, cutting one in five operational firefighters while expecting our members to do ever-more arduous work”.

Mr Lewis will give evidence to the inquiry on Wednesday, followed by Lord Wharton on Thursday.