The combined salaries of NSW Treasury's senior executives have swelled by 22.6 per cent while the government's been hawking public assets and slashing jobs to become "leaner and more efficient".

The number of top executives at NSW Treasury ballooned by 16 per cent to 144 and their combined salaries jumped by 22.6 per cent to $30.1 million between 2014-15 and 2015-16, according to annual reports.

In the financial year before that, their ranks increased by one and their overall pay went up by 2.5 per cent, in line with the 2.5 per cent cap on annual wage increases for public servants.

The 22.6 per cent hike is in stark contrast to Premier Gladys Berejiklian's statement as Treasurer last year that government processes needed to be "leaner and more efficient".