Police investigate armed robbery link

A man has been arrested over the armed robbery of a jewellery store in the Adelaide CBD, while police are investigating any possible link to an earlier armed robbery in the suburbs.

Police will allege the 26-year-old man - armed with a hammer and a replica gun -smashed display cases in the store before making off with jewellery on Wednesday morning.

In a separate incident, a woman reported she was approached by a man with a gun before her car was stolen in a suburban shopping centre car park on Tuesday night.

The man punched her in the face, stole her keys and drove away.

SA Police Detective Inspector Adam Rice said police could not rule out a link between the two incidents.

"It is early days of the investigation and we are looking to see if the the two are connected but at this stage it's too early to say," he told reporters on Wednesday.

The woman's car was found dumped in a suburban street on Wednesday and will be examined by investigators.

The man arrested in relation to the jewellery store incident is expected to be charged with aggravated robbery and property damage and is set to appear in the Adelaide Magistrates Court tomorrow.