Search crews have found an oil slick in southeast Tasmanian waters where a light plane carrying two people is believed to have crashed.
The single-engine Cessna with a pilot and one passenger on board is understood to have been tasked to capture footage of boats competing in the Sydney to Hobart yacht race as they rounded the Tasman Peninsula.
"At this stage of the search, neither the pilot nor the passenger have been found," police said in a statement late on Monday night.
About nine yachts competing in the race have diverted to the crash zone near Port Arthur to help with the search.
Race organisers are aware of the crash and provided a list of boats that were in the area at the time.
Among the yachts named was early handicap honours front runner Love & War, which since the time of the crash has slipped from the standings according to satellite tracking.
Aerial sweeps by helicopters have been suspended and will resume at first light on Tuesday.
The alarm was raised about 6.20pm (AEDT) on Monday and the Australian Maritime Safety Authority is co-ordinating the search, which includes a specialist police launch.
The oil slick has been marked by a buoy "for reference purposes", police said.
