Two men have been charged over an alleged attempt to smuggle illegal drugs hidden inside balloons into Goulburn Correctional Centre in New South Wales.

Police said a 24-year-old man was entering the centre on Sunday morning when he was noticed by a sniffer dog handler.

They said when questioned the man removed a packet hidden on his body, which allegedly contained a number of balloons containing individual packets of a substance believed to be amphetamine.

The man was arrested and taken to Goulburn Police Station.

On Sunday afternoon, a 34-year-old man was also arrested in the car park of the correctional centre.

Police said when that man's car was searched, they found an amount of cash they suspected was unlawfully obtained.

The 34-year-old man was charged with knowingly taking part in the supply of drugs, and with goods in custody.

The 24-year-old man was charged with supplying a prohibited drug and with attempting to bring something into a place of detention without authority.

Both men were refused bail, and will appear in Goulburn Local Court today.