Police searching for a 70-year-old man feared murdered while selling his boat said today that traces of blood were found on the £120,000 cruiser.

Millionaire businessmen Robert Saint was due to meet a man on Thursday to go sailing on the 42ft white vessel called Sundowner off the Sussex coast near Chichester but has not been seen since.

Detectives were continuing to question a 44-year-old man from Bognor on suspicion of murder, obtaining the boat by deception and abducting Mr Saint. He was arrested on Saturday evening.

Today police were applying to a magistrate for a warrant to continue to detain the man for further questioning.

A detailed forensic search of the boat, which was found at Itchenor, West Sussex, revealed blood in the galley.

Meanwhile officers were searching Birdham Pool harbour where Mr Saint, of Horsham Road, Steyning, had been due to meet the man with whom he had an appointment.

Detective Chief Inspector Tony O'Donnell, leading the investigation, said today: "I am now satisfied that Robert Saint was at Birdham Pool on Thursday morning.

"His car, a blue Volvo, was found parked there. We also know that Sundowner left its berth on the noon tide. We do not know whether Mr Saint, who was in the process of selling the boat, was on board.

"We urgently need any information from anyone who saw Mr Saint, possibly with another man, at Birdham on Thursday.

"We are also appealing to yachtsmen and any other seafarers who may have seen Sundowner in the Solent after it left Birdham Pool on Thursday. We believe it may have travelled as far as the Portsmouth area before returning to Itchenor."

Mr Saint, whose wife Pamela died last year, was reported missing by his son on Friday evening.

He is said to look younger than his 70 years and has silver hair with a balding patch on top, blue eyes and a light tan. He is 5ft 7in and of medium build.

He was last seen wearing a grey and white jumper with a navy blue cravat and gold neck chain with a seal pendant, a blue-and-white striped shirt and brown moccasins.

A Sussex Police spokesman said a "significant quantity" of blood was found on the boat and tests were being carried out.

He said: "At this stage we do not know whose blood it is, or even if it is human blood."