Vicky, 17, of Trimley St Mary, Suffolk, vanished early on Sunday while walking home from a nightclub in nearby Felixstowe.

Electrician Christopher Lambert, 21, was questioned for nearly 18 hours by police on Thursday before being released on bail without charge pending further inquiries.

His solicitor, Tim Ridyard, released a statement saying Mr Lambert had co-operated fully and was confident that further inquiries by police would eliminate him from the investigation.

"Mr Lambert categorically denies any involvement whatever in her (Vicky's) disappearance," said Mr Ridyard in a statement issued on behalf of Mr Lambert.

"He has co-operated fully with police officers in their investigation and has answered all questions put to him in interview. He will continue to assist the police in any way he can."

Car tests

Police officers have been with Vicky's parents, Graham, 45, and Lorinda 43, offering support.

There is still no sign of Vicky, police said, despite extensive searches and appeals for information.

Police arrested Mr Lambert, who is the son of former Ipswich Town footballer Mick Lambert, at the house he shares with his mother early on Thursday. They also took away his Vauxhall car for tests.

Detectives spent the day questioning him in Ipswich. A police spokesman said: "We want to stress that we are still desperate for any information about this incident."

Specialist search teams from the Royal Military Police in Colchester will be drafted into the investigation into the disappearance of Miss Hall, Suffolk Police said.

They are trained to search large areas of land and are expected to become involved from Monday.

About 50 officers have already been involved in the search for Vicky, as well as dogs and a helicopter.

Her father Graham has made several appeals for witnesses, and said he was praying she had been kidnapped and was still alive.

"I just want to see her walk through the door. I want her to come in and sit there and moan at me," he said.

Screams on estate

Residents on the estate told police that they heard screams and the sound of a car driving off at around the time Vicky was last seen.

A spokesman for Suffolk Police said detectives had received more than 200 calls.

Mr Hall said he and his wife were trying to support their 15-year-old son Steven and Vicky's best friend Gemma Algar, who had been walking with Vicky shortly before her disappearance.

Gemma, also 17, is Vicky's best friend and has known her since they were at primary school together.

"We have tried to reassure her. What happened was not her fault. It was just circumstances," said Mr Hall.