SA man allegedly threatened 6 women

A man has been arrested for allegedly stalking and threatening women in Adelaide.

The 36-year-old man is suspected of stalking, threatening or assaulting the women, including a 16-year-old girl, in the southeastern suburbs since Sunday.

He allegedly used a knife in some incidents.

The wanted man was spotted just before 5pm on Thursday on a train from Adelaide to Brighton.

He was arrested and is speaking to police.

Police earlier searched a unit block after reports the stolen car the man drove during the attacks had been parked there.

"We have great concerns in relation to him," a spokeswoman told reporters on Thursday.

In a recent Facebook post, the man claimed to have been "a monster and knight in shining armour".

"I've been in all gang warfare and I've saved women from being bashed in the street," he wrote.