A separate walkout by drivers at seven rail operators is already planned for this Saturday.

Both strikes will affect Greater Anglia, Great Western Railway, Hull Trains, LNER, London Overground, Southeastern and West Midlands Trains.

Motorway speed average drops as low as 14mph - rail strikes live

Staff at Avanti West Coast and Cross Country will not take part on Saturday but have now decided to take industrial action in August.

Aslef said train companies had failed to make a pay offer that would keep pace with rising living costs.

The union said workers have not had a pay rise since 2019, which amounts to a real terms cut over the last three years when soaring inflation - set to hit 11% this autumn - is taken into account.

"We want an increase in line with the cost of living - we want to be able to buy, in 2022, what we could buy in 2021," said general secretary Mick Whelan.

"It's not unreasonable to ask your employer to make sure you're not worse off for three years in a row.

"Especially as the train companies are doing very nicely, thank you, out of Britain's railways - with handsome profits, dividends for shareholders, and big salaries for managers - and train drivers don't want to work longer for less."

Network Rail previously said the company had offered workers a two-year 8% pay deal with a guarantee of no compulsory redundancies, and other benefits.

Mr Whelan said strikes were a "last resort" but "we've been forced into this position by the companies, who say they have been driven to this by the Tory government".

He added: "Let's nail a Tory lie. Wage rises aren't fuelling inflation.

"Excess profiteering is. But the government isn't asking companies to cut profits or dividend payments to help manage inflation. Wages are chasing prices, not putting them up.

"We don't see why we should forego an increase in salary to keep pace with inflation and help the privatised train companies make even bigger profits to send abroad."

Train drivers at Chiltern, Northern and TransPennine Express have until 25 August to vote on further strike action, while those at East Midlands Railway have until 19 September.

Strikes on Wednesday by 40,000 rail workers in the RMT and TSSA unions forced about half of the network to close.

Two further days of rail strikes have already been announced by the RMT for 18 and 20 August, while a Tube strike is set to affect London on 19 August.

Read more: What you need to know as rail strikes continue

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A Rail Delivery Group spokesperson said: "The action announced by the Aslef leadership shows a cynical approach to talks, a total disregard for passengers and is putting everyone's summer plans at risk.

"This action will bring the total number of strike days on the railway to 10, disrupting plans in June, July and August.

"Like any public service we have to change with the times, and it's only by making necessary reforms that we can give our people a pay rise.

"Now is not the time for further strikes, so we urge the Aslef leadership to resume talks to reach a deal that is fair to staff and taxpayers, and which secures a better, safer and more affordable railway."