Federal and NSW Labor have denied the budget’s road and rail spending is designed to safeguard government seats, with the state treasurer arguing it is needed to catch up on spending in south and north-west Sydney.

Daniel Mookhey made the comment on Wednesday after federal opposition infrastructure spokeswoman Bridget McKenzie claimed the additional $17.1 billion, 10-year infrastructure commitment in Tuesday’s budget aimed to shore up Labor seats for the election due by May 17.