Day-long strikes will hit regional train lines for more than a week in the lead-up to Christmas, as the public transport union steps up its fight for better pay.

The Rail, Tram and Bus Union (RTBU) has announced that trains to Transport Infrastructure Minister Jacinta Allan's Bendigo electorate will be the first to be hit by the series of 24-hour strikes starting next week.

Passengers on an overcrowded V/Line train. Credit:Joe Armao

Bendigo line trains will be affected by the strikes from 12am on Wednesday, December 11, as will trains to Swan Hill.

Staff working on the Ararat, Maryborough and Ballarat lines will strike on Thursday, December 12, while trains to Traralgon and Bairnsdale will be affected by the industrial action on Tuesday, December 17.