Two hikers missing in South Australia mountain range overnight

Two hikers are missing near Cambrai in South Australia's Mt Lofty Ranges in extremely cold conditions.

The men set out on a day-walk in the Marne Valley Conservation Park on Tuesday, after parking a car at both ends.

At about 5.30pm, one of them rang his wife saying they expected to be late.

She contacted police when they failed to return six hours later.

Police on Wednesday said concerns are held for the hikers, who were not equipped for an overnight stay in the extremely cold conditions.