A man with a rocket launcher and other firearms has been caught by police who were making "routine enquiries" in South Australia.

Police said they attended an address at Holden Hill north of Adelaide on Monday to speak with a 33-year-old man and saw a firearm and drug-related equipment.

A search of the house ensued and police found two firearms, ammunition, a silencer, multiple knives, methamphetamine, cannabis and a rocket launcher.

The man was arrested and charged with firearms offences as well as possessing prescribed drugs for sale and prescribed equipment.

He was refused bail and, after appearing in the Elizabeth Magistrates Court on Wednesday, was remanded in custody to make a second court appearance at the Adelaide Magistrates Court on June 30.