Two Italian yachtsmen stranded on their yacht midway between New Zealand and Chile have been rescued.

The crew of the oil tanker Hellespont Trooper plucked Pietro Fresi, 64 and his son Vittorio Fresi, 34, to safety at 8.30am on Thursday.

The pair had been awaiting rescue since they sent a mayday call early on Monday when the mast snapped and the engine failed on their 10.4m Italian-registered yacht Onitron, stranding them more than 2000 nautical miles from New Zealand.   

Rescue Co-ordination Centre New Zealand (RCCNZ) spokesman Ross Henderson said the tanker reached the pair about midnight, but the crew were unable to rescue the sailors until Thursday morning, due to strong winds and heavy seas.

RCCNZ contacted the oil tanker and organised the rescue of the sailors in the eastern reaches of New Zealand's search area.

"The tanker's initial position was 800 nautical miles from the yacht, and it has been steadily making its way towards the stranded sailors over the past two-and-a-half days," Henderson says.

"The two men, who maintained good spirits throughout their ordeal, were well-equipped, experienced sailors in good health."