Women with silicone breast implants made by a French company do not need to have them removed, UK officials say.
French authorities will decide shortly whether women should have implants supplied by Poly Implant Prothese (PIP) removed, amid fears of health risks.
But the UK's Medicines and Healthcare products Regulatory Agency (MHRA) says none of the evidence into possible links with cancer supports removal.
It is thought up to 40,000 British women have the PIP silicone implants.
Women with implants who are concerned have been told to contact the surgeon or clinic that fitted them. According to the MHRA, the vast majority (95%) of the implants were fitted privately, with less than 5% used within the NHS.
In the UK, more than 250 British women are to start legal action, said a lawyer. Over half had suffered ruptured implants, Esylllt Hughes told the news agency AFP.
PIP used non-medical grade silicone believed to be made for mattresses, according to the British Association of Aesthetic Plastic Surgeons (BAAPS). This meant the low-cost devices were more likely to split.
Eight cases of cancer, mainly breast cancer, had so far been reported in patients with PIP implants, France's Director General for Health, Jean-Yves Grall, told the Liberation newspaper. A ninth patient in Gers died of cancer last year.
But the head of France's National Cancer Institute, Dominique Maraninchi, said last week the cases were not necessarily linked to faulty implants.
The MHRA said there was "insufficient evidence to indicate any association with cancer" after reviewing the available evidence with the relevant UK professional bodies.
It said it had worked in consultation with the cancer registry as well as professional bodies for breast surgery and surgical oncology.
"The MHRA's current advice to women with any type of breast implant continues to be that women who are concerned about their breasts or think that their implants may have ruptured, should seek clinical advice from their implanting surgeon," the agency said.
It added: "There is currently no evidence to support routine removal of PIP breast implants."
A statement from the British Association for Plastic, Reconstructive and Aesthetic Surgeons (BAPRAS) said: "BAPRAS has not yet seen the evidence demonstrating that health problems may have been caused by PIP breast implants and will fully assess any that becomes available.
"We currently believe that the expected announcement from French medical authorities will be a precautionary measure.
"Surgeons will be in contact with any patient who has received this type of implant if any action is required."
Douglas McGeorge, consultant plastic surgeon and former president of the British Association of Aesthetic Plastic Surgeons (BAAPS), said patients with breast implants should check whether they have had one from PIP.
"The message here is not to panic," he said.
"The advice is unchanged. Women with PIP implants should be checked by the clinic where they had their surgery and can then be monitored afterwards.
"These implants have a higher failure rate so there will be women who might choose to have their implants removed before that happens, whereas others will be happy to be monitored."
More than 300,000 implants are believed to have been sold globally by PIP over the last 12 years.
About 30,000 have been fitted in France, out of which more than 1,000 have ruptured.
PIP went into administration last year and the use of its implants was banned.
French authorities say they will decide on Friday whether to ask the women given that type of breast implant to have them removed.
The French government has formed a special committee to look at the issue.