Passengers have been warned to expect disruption as strikes by thousands of London bus drivers will affect routes for seven days in December.
Drivers from the Unite union of two employers, Abellio and Metroline, will strike for three days from Thursday December 1 to Saturday December 3 over pay disputes.
Transport for London (TfL) said customers in north, west and south London should check before traveling and allow extra time for their journeys.
While some passengers have transport alternatives on the metro and train services, with more than 100 routes shut down, congestion on the remaining routes and buses is likely to be significant.
Last-minute talks in Acas between Unite and Metroline are due to take place on Wednesday, with the union still negotiating with Abellio.
Metroline workers, who cover north and west London routes, are due to strike again on December 8-9 and 15-16.
Abellio bus workers, mainly based in the south and west of the capital, went on a three-day strike at the end of November and will also strike on December 9-10 and 16-17.
The latest action by bus workers at both companies will coincide with the RMT rail strikes, which are also likely to affect some Underground, London Overground and Elizabeth line services in west London.
Thousands of RMT members working for Network Rail and 14 rail operating companies will strike twice for two 48-hour periods a week. The first strikes, on 13-14 and 16-17 December, will cause disruption for six consecutive days in the run-up to Christmas, with a similar effect on services through further strikes on 3-4 and 6-7 January.
Unite general secretary Sharon Graham described Metroline, owned by Singapore-based ComfortDelGro, and Abellio as “exceptionally wealthy companies” that could afford to pay drivers like others in the capital.
Louise Cheeseman, Director of Buses at TfL, said: ‘We apologize for any disruption caused to Londoners, especially those in west London who may be affected by the two sets of strikes. There will still be options for people to travel to affected areas, but other routes may be busier than normal.
“We encourage everyone in these areas to plan ahead, check before you travel, and allow extra time for travel.”