The experts, appointed two years ago, said tests had shown toxic side-effects were few in number and questionable in significance.

It is thought the findings - although not legally binding - could have a significant bearing on thousands of court cases throughout the world, where women maintain they have suffered after breast implant operations.

One company, Dow Corning, has already offered more than $3bn in settlement of actions against it.

Lawyers representing those affected attacked the study as too narrow and accused the experts of failing to address one key question.

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US Judge Sam Pointer, who ordered the inquiry, is overseeing federal class-action suits against implant makers Bristol-Myers Squibb, Minnesota Mining and Manufacturing, Dow Corning and medical products company Baxter International.

In their report, the experts said: "The main conclusion that can be drawn from existing studies is that women with silicone breast implants do not display a silicone-induced systemic abnormality in the types of functions of cells of the immune system."

Lawyer Rick Laminack, whose Houston firm represents about 1,500 breast implant recipients, said the report failed to address the critical issue of implant deterioration.

"This report does not deal with the fact that implants break," he said.

"They rupture, they leak, they fall apart. This report by the science panel does not deal with that subject, which is why we have lawsuits.

"This report focused on some very narrow questions."

The panel of scientists from US universities gathered evidence from medical experts for both sides and examined about 2,000 documents.

They were ordered to look for relationships between implants and a series of disorders, including lupus, Sjogren's syndrome, immune system dysfunctions, scleroderma and rheumatoid arthritis.

With the exception of Sjogren's syndrome, the chief symptom of which is dry mouth, the panel found no links between the implants and the illnesses.