A man accused of converting toy guns into air rifles has been charged with firearms offences by South Australian police.

The 29-year-old man from Rosewater in Adelaide was charged after Riverland police investigated a shed break-in at a property at Monash.

Officers found a number of Nerf-style toy rifles and pistols which had been modified.

Police said during a later search of a Rosewater house they found items allegedly used to make the conversions.

The man was given bail and is to face court in April charged with manufacturing proscribed firearms and possessing firearms without a licence.

Police allege he had been making air rifles for several years.

They said gun owners were required to be licensed and more information about firearms laws was available at the police website.