Thousands of London tube station workers are preparing to strike on the Monday following the Queen's Platinum Jubilee long weekend.
Tube union RMT has criticised Transport for London (TfL) for threatening hundreds of job losses on the network.
General secretary Mick Lynch said: "TfL is trying to bulldoze through 600 job losses on London Underground and our members are not prepared to accept that.
"Station staff play a crucial role in serving the travelling public and were heroes during the 7/7 terrorist attacks.
"Instead of seeking to cut jobs, TfL and mayor Sadiq Khan need to put further pressure on the government to secure increased funding for the network so we can have a properly staffed modern 21st century tube."
The 24-hour walkout is set to take place at 12.01am on June 6.
It could see 4,000 RMT members strike; as has been reported elsewhere, this would likely force the closure of most stations in zone 1.
Back in March, two network-wide protests saw 200 stations shut and £13m in lost TfL revenue.
RMT has also announced an overtime ban from June 3 - July 10.
In response to the news, TfL's chief operating officer Andy Lord described the action as "unnecessary".
Expressing his disappointment, he said the walk out was designed to disrupt the Jubilee weekend: "It is particularly surprising that the RMT has threatened to spoil this moment when the nation is coming together as nobody has or will lose their jobs as a result of the proposals we have set out and there have been no proposals on pension changes.
Mr Lord added: “If the RMT chooses to go ahead with this unnecessary action, we will do everything we can to minimise any disruption and ensure everyone can still make the most of the capital throughout the Jubilee weekend."
The chief operating officer confirmed that TfL's financial issues - exacerbated by the "devastating impact" of Covid-19 - are driving the need for restructure.
TfL plans to cut hundreds of jobs from its Tube services, due to its financial issues, by not replacing staff when they leave or retire and not filling some current job vacancies.
It warns that the industrial action will further impact TfL's finances.
The June 6 action is separate from smaller industrial action planned at Euston and Green park stations on June 3.
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