The search for a swimmer missing off the Mornington Peninsula has been called off due to fading light.

Search and rescue efforts for the 23-year-old Narre Warren man began about three hours earlier he and his two friends were caught in a rip on Sunday afternoon.

Police believe the missing man and his two friends were swimming about 5.30pm near Portsea when they were swept away.

Two of the men have been found – one of whom was flown to hospital in a serious condition. At 9.30pm on Sunday the 22-year-old man from Cranbourne West remained in a serious but stable condition at the Royal Melbourne Hospital.

The other – a 23-year-old man from Cranbourne – did not require medical treatment.