Metro has admitted in leaked correspondence that maintenance failures on its part caused two derailments on the same bend within five days last summer.

Trains came off the tracks twice on the tightest curve on Melbourne's rail network, near Rushall station in Fitzroy North, on February 6 and February 10.

The train that derailed near Rushall station in February. Credit:Luis Ascui

First a passenger train and then a track maintenance vehicle came off the rails because the track were not greased sufficiently and the tracks were in poor condition, according to a report by a senior Metro manager, obtained by Fairfax Media.

The report, by Metro manager of safety, environment and risk Matt Sekulitch​, said the cause was "a combination of lack of lubrication and track condition, which created an upwards component of lateral force exceeding downwards force on the wheel".