The state's passenger rail operators are struggling to retain train drivers, undermining efforts to hire significantly more of them to avoid a repeat of widespread disruptions to services early this year.

Sydney Trains and NSW Trains recruited 139 drivers in the seven months to January but had 83 leave permanently or shift to other internal roles, resulting in a net increase of just 56 in the period, according to figures released to Labor under freedom of information laws.

Train drivers are offered higher rates of pay in Victoria and Queensland to operate driver-only services. Credit:Kate Geraghty

Sydney commuters experienced widespread disruptions to train services in January, which a high-level report into the incidents later blamed partly on a lack of train crews.

The latest figures also show the state-owned rail operators had a net increase of 32 train drivers in the 2016-17 financial year, following three years of significantly more staff exiting the roles than were recruited.