The man accused of murdering nine-year-old Charlise Mutten, whose body was found in a barrel in bushland in the Blue Mountains in NSW, is facing more charges.

Justin Laurens Stein, 31, was on Thursday charged with two counts of possessing an unregistered firearm, two counts of possessing an unauthorised firearm, possessing ammunition without licence or permit and aggravated break and enter in company.

He was also charged with two counts of possessing child abuse material for unrelated matters.

Mr Stein, who is in custody, will appear before Penrith Local Court on Friday.

Nine-year-old Charlies was reported missing on January 14, while holidaying at Wildenstein Private Gardens at Mount Wilson.

A five-day search of bushland ended with her body being found in a barrel dumped near the Colo River north-west of Sydney.

NSW Police later said an autopsy found she had died of a gunshot wound.