ASLEF announced last month that its members would withdraw non-contractual overtime, known as rest-day working, with 16 of the country's 35 rail operators from Monday 3 July to Saturday 8 July.

Train companies affected are: Avanti West Coast; Chiltern Railways; Cross Country; East Midlands Railway; Greater Anglia; GWR; GTR Great Northern Thameslink; Island Line; LNER; Northern Trains; Southeastern; Southern/Gatwick Express; South Western Railway main line; SWR depot drivers; TransPennine Express; and West Midlands Trains.

Full list of July strike dates and services affected

The action may impact visitors to the first week of the Wimbledon tennis tournament.

It is understood that there have been no negotiations between the union and the rail operators since the action was announced on 19 June.

Mick Whelan, ASLEF's general secretary, told Sky News' Kay Burley on Monday that he was prepared to take action for two decades until an agreement was found.

"This can't go on forever, we want to resolve this no matter how badly [the government] treated us, no matter how badly they behaved," he said.

"It is still our intention to find the resolution... we're going to keep taking action until someone listens to us."

Mr Wheelan claimed he has been "ignored" by Transport Secretary Mark Harper and Rail Minister Huw Merriman, who he said he hadn't spoken to for around six months.

He told Sky News: "If we're whistling in the wind for five years, 10 years, 20 years to get somebody to table this, it will be resolved at some point and somebody will talk to us properly at some point."

When asked if he was prepared to take action for two decades, he replied: "Quite possibly, because the option is what, to do nothing?"

He hit out at the government for "not being interested in the people, the workers of this country" and said it "doesn't give a damn about key workers that put themselves at risk during the pandemic".

Speaking earlier, Mr Whelan said there was "no alternative" but to take action.

"We have continually come to the negotiating table in good faith, seeking to resolve this dispute.

"Sadly, it is clear from the actions of both the train operating companies and the government that they do not want an end to the dispute.

"Their goals appear to be to continue industrial strife and to do down our industry.

"We don't want to inconvenience the public.

"We just want to see our members paid fairly during a cost of living crisis when inflation is running at above 10%, and to not see our terms and conditions taken away.

"It's time for the government and the companies to think again and look for a resolution."

Culture Secretary Lucy Frazer insisted the government is "helping facilitate discussions" and described the strikes as "really disappointing".

"We are, of course, in a cost of living crisis where we need to keep inflation down," she said.

"That means we need to control public spending. Train drivers get, on average, around £60,000. And I do think it's important that they come to the table so that they don't disrupt the journeys of thousands, millions of people across the country."

When asked if £60,000 was enough, she added: "Well, that's a matter for the unions and those employing the train drivers.

"But of course, I suspect many people around the country would think £60,000 was quite a lot of money."

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A spokesman for the Rail Delivery Group said: "ASLEF's leadership continues to disrupt customers' travel plans.

"They rejected a fair and affordable offer without putting it to their members which would take average driver base salaries for a basic salary for a four-day week without overtime from £60,000 to nearly £65,000 by the end of 2023 pay awards.

"Train companies will work hard to minimise the impact of the overtime ban but the impact of ASLEF's action will vary across the 16 train operators and customers are advised to check their travel plans before setting off.

"We ask ASLEF to recognise the very real financial challenge the industry is facing and work with us to deliver a better railway with a strong long-term future."