The announcement by the Rail, Maritime and Transport union (RMT) was made just hours before rail workers downed tools for a day of industrial action today.

The new strike on 19 August is about a dispute with Transport for London (TfL) over pensions, jobs and conditions.

RMT says the latest call for action has been prompted by “TfL’s refusal to share the details of a draft government proposal they received regarding funding of the transport system in the capital, in secret and without any discussion with their recognised trade unions.”

RMT says London Underground Ltd (LUL) and TfL management have consistently refused to engage in discussions around safeguarding jobs, pensions and conditions on the “spurious grounds” that they are unable to give any assurances to our members until they have a financial settlement with the government.

The union is giving TfL until 2 August to assure the union that there will be no reduction in jobs, no detrimental changes to pensions, and no changes to working conditions imposed.

RMT general secretary Mick Lynch said: “Our members will once again take to picket lines in this important dispute over pensions, jobs and conditions. They have been messed around by TfL and mayor Sadiq Khan. And to add insult to injury they have not seen the detail of this funding letter from government.

“Unless there can be assurances made about jobs, pensions and detrimental changes to working conditions, then our strike on August 19 will go ahead.”

The new tube strike is in addition to numerous days of industrial action by transport workers over the coming weeks.

More than 40,000 members of RMT and the Transport Salaried Staffs’ Association (TSSA) are striking today after talks failed to resolve a dispute over pay, jobs, and conditions in the rail industry. The walk-out is affecting rail services across the country.

About 6,000 train drivers belonging to the Aslef union across eight train companies will join the dispute when they strike this Saturday, 30 July.

A repeat of today’s action by RMT members at Network Rail and 14 train companies is also planned for 18 and 20 August.

Transport secretary Grant Shapps accused unions of “trying to cause as much disruption as possible to the day-to-day lives of millions of hardworking people around the country” and urged unions “to stop holding the country to ransom with the threat of further industrial action and get off picket lines and back around the negotiating table”.