Drug dealers would be held responsible for any deaths they cause at music festivals and could face up to 25 years in jail, under new plans which the NSW government says will boost safety and save lives.

Following a month-long investigation by an expert panel sparked by the deaths of two young people at Defqon.1, Premier Gladys Berejiklian on Tuesday announced she had accepted in-principle its seven recommendations.

She said the government would introduce a new offence for those who supply illegal drugs for profit and cause someone to die.

"The Attorney-General and the police force will be working together ... we envisage it will be anywhere between grievous bodily harm, which is 10 years [maximum in prison], and manslaughter, which is 25 years [maximum in prison], so somewhere in that range," Ms Berejiklian said.