The NSW police chief has says too many accused criminals have been released on bail in recent months but he's promising to fix it.

Despite "positive" changes to the state's bail laws and extensive training, Police Commissioner Mick Fuller feels mistakes are still being made.

NSW Police Commissioner Mick Fuller. Credit:AAP

"We're not going to get every one right, but probably in the last six months there's been too many that I think - legislatively and morally - that we should've refused bail on these people," he told 2GB radio on Monday.

"Clearly, we need to do more work to empower the custody officers to make the right decision."