Train companies have started cancelling services over the Bank Holiday because of a planned strike by thousands of Network Rail (NR) workers in a row over pay, even though peace talks are continuing.

West Coast main line operator Virgin Trains scrapped all services on Monday and Tuesday and warned it would only be able to run a very limited number of trains on its East Coast line over the two days.

An outline of how the strike will affect all train companies is expected today, but passengers were warned to expect severe disruption if the 24 walkout goes ahead from 5pm on Monday. Talks to avoid the strike were adjourned last night and are due to resume at 9am today.

CrossCountry Trains, Chiltern Railways, Arriva Trains Wales, First Great Western and ScotRail were among those giving passengers an early idea of the travel chaos they can expect.

Passengers were being advised not to travel unless "absolutely necessary", with widespread cancellations expected, leading to packed trains.

A legal challenge by NR against the Transport Salaried Staffs Association (TSSA) ballot is listed this afternoon in the High Court.

NR also urged train passengers to be prepared for the strike, saying it could not bank on unions calling off the planned stoppage.

The two sides were continuing to hold talks at the conciliation service Acas, and NR said its negotiators will be available into the weekend if necessary to try to head off a strike.

Chief executive Mark Carne said: "We are continuing to talk with the unions and we believe there is a settlement to be had. I sincerely hope we can reach one and my team will be available all week, and into the weekend if necessary, to find a deal to prevent strike action.

"From the very start of negotiations we made clear that we want to reward our staff for the incredible job they do, but that any pay rise needs to be linked to smarter, more effective ways of working.

"We can't bank on the unions calling off the strike, so we are now concluding our contingency plans so passengers can make decisions about their journeys.

"If the strike goes ahead, it's important that people check before travelling and are aware of the special measures put in place by train operators for people who have already booked tickets."

Full details of amended timetables and what services will run, when and where, are expected to be available from train operators by Saturday, with "overviews and summaries" available from today.

Members of the Rail, Maritime and Transport union and the TSSA have rejected a four-year pay deal of £500 followed by three years of rises in line with RPI inflation.

Train operators are working with NR on contingency plans, which will be "fine-tuned" over the next few days.

RMT general secretary Mick Cash said: "RMT is continuing to push for a negotiated settlement through the Acas talks and the union is available right the way through the weekend to keep that process going, if necessary.

"In the meantime, our picketing arrangements are in place and the response coming back from our members is one of rock-solid support.

"We would remind the public that we have been forced into this dispute through a wholly-unwarranted attack on safety-critical jobs, pay and working conditions that would seriously undermine the safety of passengers on our railways into the future.

"RMT members are standing up for the principle of a properly staffed and resourced railway where safety comes first and where corners aren't cut to hit budget targets."

Virgin said: "Customers planning to travel on the affected dates will need to make alternative arrangements. If you are planning to travel on Sunday May 24 or Wednesday May 27 we recommend that you check before you travel for more information on how your journey may be affected.

"We appreciate that many customers will have their travel plans disrupted by the planned industrial action, so train companies have agreed to put in place special arrangements to make it easier for you to complete your journey."

The firm added: "If the strike is called off with enough notice, we would be hopeful of running a near normal service."

If the strike goes ahead, it would seriously affect the ability of fans of Middlesbrough and Norwich City football clubs to travel to Wembley for their teams' Championship play-off final starting at 3pm on Monday.

Abellio Greater Anglia said it was putting on special trains for Norwich fans but warned of the threat of industrial action. Engineering work, in any case, will mean Greater Anglia trains to and from London on Sunday and Monday will terminate and start at Stratford station in east London, not London Liverpool Street.

The train drivers' union Aslef added to the threat of disruption by announcing that its members on Southern Railways had voted to go on strike in a separate row over pay.

A spokesman for the Rail Delivery Group, which represents Network Rail and train operators, said: "Operators and Network Rail are still working together to finalise plans for services on Monday and Tuesday in the event of a national rail strike and we know passengers want concrete information as soon as possible.

"A specific strike timetable will be made available at the earliest opportunity once it is clear whether the strike will or will not go ahead."

Heathrow Express said it plans to run services every 15 minutes during shortened operating hours if the strike goes ahead.

The normal timetable will be in operation until 6.30pm on Monday and on Tuesday services will run between 7.30am and 6.30pm.

Trains between Heathrow terminals are also set to finish at 6.30pm on Monday and run between 7.30am and 6.30pm on Tuesday.

Should the strike go ahead, the Heathrow Connect stopping service between Paddington and Heathrow will not run on Monday and Tuesday.

Keith Harding, operations director for Heathrow Express, said: "Our advice to customers using the Heathrow Express on Monday and Tuesday is: Check before you travel."