More than 1,600 London bus drivers are set to take strike action later this month in a dispute over pay.
Members of Unite employed by London United will walk out on 19 August and 20 August.
The union said the action was in response to London United offering a pay increase of 3.6% in 2022 and a further 4.2% raise next year.
Officials argue the soaring rate of inflation means the proposal amounts to a "real-terms pay cut".
The industrial action will affect workers based in depots in Fulwell, Hounslow, Hounslow Heath, Park Royal, Shepherd's Bush, Stamford Brook, and Tolworth.
'Trade union tin'
Unite general secretary Sharon Graham said: "Unite's members play a crucial role in keeping London moving and they are not going to accept seeing their pay constantly eroded.
"Unite does what it says on the trade union tin and always defends the jobs, pay and conditions of its members.
"Our members at London United will receive the union's complete support until this dispute is resolved and a fair pay offer secured."
The strike action will coincide with walkouts on the London Overground and Network Rail.
Transport for London (TfL) has been approached for a comment.