Boris Johnson is to write letters of apology to the families of 10 people killed during a British army operation in Ballymurphy in 1971 after his initial attempt to apologise backfired and angered them. The Northern Ireland secretary, Brandon Lewis, made a public apology on behalf of the UK government in the House of Commons on Thursday, two days after the conclusion of an inquest into the shootings, and said the prime minister would write to the families. The families, however, are still requesting a public apology from Johnson as the head of the government, a spectacle Downing Streets appears to be trying to avoid. “The families say this should come directly from the British prime minister,” Padraig Ó Muirigh, a solicitor representing them, said after Lewis’s statement. David Cameron set a precedent by apologising in the House of Commons in 2010 after the Bloody Sunday inquest, he said. “Johnson should do the same.” An inquest on Tuesday found that the army’s use of force during street disturbances in Ballymurphy, a west Belfast Catholic neighbourhood, was unjustified and that the 10 people killed had no paramilitary links and were “entirely innocent”. The inquest report concluded that soldiers killed nine people, including a parish priest, Hugh Mullan, and Joan Connolly, a mother of eight. The coroner, Mrs Justice Keegan, was unable to establish who killed the 10th victim, John McKerr. The other fatalities were Francis Quinn, Noel Phillips, Daniel Teggart, Joseph Murphy, Edward Doherty, John Laverty and Joseph Corr. “I want to put on record the government’s acknowledgment of the terrible hurt that has been caused to the families,” Lewis told MPs, and named the victims. “The events at Ballymurphy should never have happened. The families of those who were killed should never have had to experience the grief and trauma of that loss.” Lewis tacitly acknowledged debunked army claims that some of the dead had been armed IRA members. “They should not have had to wait nearly five decades for the judgment this week, nor have been compelled to relive that terrible time in August 1971, again and again in their long and distressing quest for truth.” He said the vast majority of security force personnel served with dignity and professionalism during the Troubles, but that in some cases there were “terrible errors”. Lewis said Johnson would write personally to the families and said the prime minister had apologised unreservedly on behalf of the state during a phone call on Wednesday with Arlene Foster, Northern Ireland’s first minister, and Michelle O’Neill, the deputy first minister. Colum Eastwood, the SDLP leader and MP for Foyle constituency, which covers Derry, said the shooting of Connolly was not an error but “sheer bloody murder” and called on the prime minister to “come out of hiding” and meet the families. Some of the families have rejected Downing Street’s statement on Wednesday – a readout of Johnson’s phone call – as an attempt to push his apology under the carpet. Many believe the government is waiting for the focus on Ballymurphy to pass before detailing plans to shield army veterans from prosecution for alleged crimes during the Troubles, a de facto amnesty that could extend to republican and loyalist paramilitaries. Lewis reiterated that the government intended to overhaul the system for handling so-called legacy cases. “With each passing year, the integrity of evidence and the prospects of prosecution do diminish, and the government is not shrinking from those challenges,” he said. “It is determined to address them in a way that reflects the time that has passed, the complexity of Northern Ireland’s troubled history and the reality of the compromises that have already been made.”