Train drivers are threatening to boycott Frankston, Dandenong and Pakenham services next week, saying they will not drive on newly laid South Yarra tracks as they have not had proper training.

It means rail commuters from the city's south-east who have been forced onto buses for most of January could face further disruptions on the week their trains are supposed to finally resume.

Frankston, Dandenong and Pakenham train services are set to resume next week after a four-week shutdown, but drivers are threatening to boycott these services in a dispute with Metro Trains over inadequate training.

More than 100 drivers have complained to the Rail, Tram and Bus Union, saying they are not equipped to safely run services through a new section of track built between South Yarra and Hawksburn as part of the Metro Tunnel works.