London Underground workers will stage two further strikes this month as part of the dispute over all-night Tube services.

Workers will stop work for 24 hours from 9pm on August 25th, and again from 9pm on August 27th, according to the Rail, Maritime and Transport Union (RMT).

It comes after two earlier strikes over the past month caused major travel disruption for commuters in the British capital.

Unions are locked in a dispute over pay and shift arrangements for the new 24-hour Tube service, which is due to be launched at weekends.

RMT general secretary Mick Cash said staff are angry that their "grievances are being ignored and dismissed by both the Mayor and his officials" during ongoing negotiations.

"There has been no substantial move as of today from London Underground to make progress towards a negotiated settlement," he added.

"That is why we have no option but to strike again. It is ridiculous that the job cuts programme for fleet, engineering and station staff is also still being bulldozed through against this background."

"The night Tube plan has been botched from the off."

"The basics haven't been done and those who will pay for this shambles will not only be our members but the London daily travelling public who cough up a fortune and who will find their safety and the reliability of the service compromised from September 12 onwards."

"Running Tube services with fatigued and burnt-out staff is a recipe for disaster."

Last week's Tube strike caused severe travel disruption with lengthy delays, queues and traffic jams reported across the capital.

As the strike came to a close, evening commuters were caught in 894 separate traffic jams.

The navigation software makers TomTom said the traffic jams caused around 500 miles of tailbacks in London.

Large queues also built up for the city's buses and trains.