Union bosses have accused the government and rail firms of exploiting the pandemic to force through changes to conditions, with one claiming that drivers were so short of breaks they had to rely on incontinence products. In evidence to MPs on Wednesday, they also accused the government of meddling in negotiations over pay, despite ministers’ insistence that they were not involved. Unions and train companies have been locked in a dispute over pay as workers seek increases amid rapid inflation that has eroded real pay and caused a cost of living crisis. Members of the RMT union staged three days of walkouts in late June that brought large parts of the British network to a halt. On Wednesday, the union announced a further day of strike action to be held on 27 July. Leaders at the Aslef union representing train drivers will meet on Thursday to discuss their own strike dates after workers at eight train-operating companies voted overwhelmingly for action. Eddie Dempsey, the RMT’s senior assistant general secretary, told the Commons transport select committee there had been “some progress” in talks, but claimed the government was “using the health emergency” to force through changes. Mick Whelan, the general secretary of Aslef, told MPs there was a “resounding willingness among our members” to pursue industrial action, alleging that some drivers, confined to cabs for long periods without breaks, had been forced to use “Tena products” – an incontinence brand. “People are using the pandemic as an excuse to decimate terms and conditions and force through things,” he said. The evidence came a day after Network Rail, the company which runs rail infrastructure in Great Britain, made an improved formal pay offer to the RMT. The union rejected it, saying it amounted to a real terms pay cut. Dempsey claimed the RMT’s pay talks were being constrained by Network Rail’s need to run decisions by the government, which insists that it cannot intervene directly. He told the committee that Network Rail negotiators “often have to leave the room to go and have conversations” with government figures. He added that the transport secretary, Grant Shapps, had made “unhelpful comments, incendiary comments” about striking workers, and said there had been successful pay deals with employers that did not answer to the Department for Transport, adding: “Everywhere the DfT is not involved we’re managing to reach settlements, avoid disputes.” Tim Shoveller, Network Rail’s chief negotiator, told the committee that the body had been unable to make the pay offer before the strikes, but that there had been a “very, very positive week” of negotiations since then. He said the railways needed to cut costs to adjust to lower commuter numbers since the start of the pandemic. A DfT spokesperson said: “It is a matter for unions and employers – not government – to engage in meaningful talks on modernisation practices to avoid damaging strike action and prevent chaos on the railways. Government is not the employer here.” However, the spokesperson also said it was “important that ministers remain close to the ongoing situation regarding negotiations”.