LONDON, England (CNN) -- Divers have searched on seven days since late January for missing British girl Madeleine McCann in a reservoir near the Portuguese resort where she disappeared, a member of the dive team told CNN on Wednesday.

A handout photo, released September 16, 2007, of missing child Madeleine McCann.

But so far they have come up only with some cord, a sock and plastic bags.

The search, organized by a Portuguese lawyer who hired private divers, is due to resume Thursday, said the dive team member, Martyn Falkous, in a telephone interview. But he added it is unclear if it will continue after that.

The search was not requested by the McCann family.

Madeleine was reported missing by her parents last May 3, just days before her fourth birthday. At the time, they were on a family vacation at a resort in Praia da Luz, in southern Portugal.

Since then, her parents, Kate and Gerry McCann, have garnered international support in an effort to find their daughter. They visited briefly with Pope Benedict XVI, got an appeal by footballer David Beckham, and hired a Spanish detective agency.

But Portuguese investigators named the McCanns as official suspects last September. They deny any involvement in the disappearance, saying they believe Madeleine may have been abducted.

The search at the Barragem do Arade reservoir, about 30 kilometers (19 miles) from Praia da Luz, is the initiative of Portuguese lawyer Marcos Aragao Correia, who told CNN he has never spoken to the McCanns but has sent them two letters and without receiving a reply.

Correia said, in a telephone interview, that he decided to search the reservoir after getting tips from his "underworld" sources, whom he declined to name publicly. But he said the Portuguese police and the McCanns' detectives know who they are.

"We've been contracted by a lawyer who's got some inclination that Madeleine was dumped in there," said Falkous, the diver.

The first search at the reservoir lasted four days in late January and early February, and the second search began last Monday, Falkous said.

Divers have "been picking up unnatural objects" from the reservoir's floor, including the cord, a sock and plastic bags, Falkous said.

Correia said they have found four strings, each with different lengths, and a sock. He said the items have been turned over to the McCanns' detectives, but Falkous said the items were given to "authorities."

Six divers have been involved each day, Falkous said. Because it is a very large reservoir with no visibility, he said, divers have concentrated only on the "very likely" places that a body might be found. He added that a complete search of the lake would take much longer.

McCann family spokesman Clarence Mitchell told CNN, "Correia (the lawyer) is entitled to search the area, but we do not accept the premise that Madeleine is dead, and there is no evidence to indicate her body is in this lake. Neither police nor the McCann investigators are present at the search."

Falkous, a British national from North Yorkshire who's lived in Portugal for seven years, said his dive firm cut its price by about half in an effort to help out.

The disappearance of the girl "has affected everyone down here," he said. "Everyone wants to see closure to it, one way or the other. It's a safe place. People are shocked it happened."

Correia said he paid €5,000 ($7,750) for the first phase of the search and the Portuguese Society of Engineering and Construction is helping to defray the costs.

Mitchell said police in Leceistershire, England, where the McCanns live, recently sent an officer to Portugal to meet with Portuguese police regarding another possible round of interviews with friends who dined with the McCanns at the resort on the night Madeleine went missing.

She and her two younger siblings were reported to be sleeping alone in the family's rented quarters at the resort, while her parents and their friends dined at a nearby resort restaurant.

Mitchell said it appears that the Portuguese police will conduct new interviews with the family friends, but probably not until after Easter. E-mail to a friend

CNN's Emily Chang, Isa Soares and Laura Perez Maestro, in London, contributed to this report

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