The full timetable will be published on Friday but operators including Southern, Northern, TransPennine and Transport for Wales have already told passengers not to attempt to travel on strike days. Network Rail confirmed that large parts of Great Britain will have no passenger services on strike days, including locations such as Penzance in Cornwall, Bournemouth in Dorset, all of Wales west or north of Cardiff, and no passenger trains running north from Glasgow or Edinburgh. With backup staff for signalling, about 20% of trains will run on mainlines and urban areas on the strike days – 21, 23 and 25 June – while services will start later in the morning, with about 60% of the schedule on the subsequent days. Network Rail’s chief executive, Andrew Haines, described the strike by 40,000 RMT workers as a “high-stakes gamble” by unions, and said it would cost the industry £150m and make a pay increase harder. Haines said proposals to modernise to increase safety and productivity were meeting “intransigence … even when terms and conditions are patently anachronistic”. He said talks would continue but added: “We haven’t yet seen movement that gives us real hope.” The RMT called for direct talks with the government, saying it was “clear that the Treasury is calling the shots”. Mick Lynch, the RMT’s general secretary, wrote to the transport secretary, Grant Shapps, to seek an urgent meeting, saying: “In effect, in recent weeks the union has been negotiating with the government but the government have not been in the room.’’ The last meeting between unions and the government was with the rail minister Wendy Morton in March. Labour accused the government of a “dereliction of duty” for failing to hold talks to resolve the strike. The shadow transport secretary, Louise Haigh, said it was “frankly extraordinary” and wrote to Shapps calling on him to convene urgent talks. Sign up to the daily Business Today email or follow Guardian Business on Twitter at @BusinessDesk The number of passenger services on the strike days is expected to be limited to about 4,500 compared with 20,000 normally The last services between London and Scotland will leave by 2pm, while most intercity trains in England will have their final departure mid-afternoon. Steve Montgomery, who chairs the industry body the Rail Delivery Group, said: “These strikes will affect the millions of people who use the train each day, including key workers, students with exams, those who cannot work from home, holidaymakers and those attending important business and leisure events. “Working with Network Rail, our plan is to keep as many services running as possible but significant disruption will be inevitable and some parts of the network will not have a service, so passengers should plan their journeys carefully and check their train times.”