LONDON/PARIS (Reuters) - Fears over the safety of silicone breast implants made by a now defunct French firm spread to Australia, South America and across Europe on Thursday as French officials prepared to decide if thousands of women should have their implants surgically removed.

The silicone gel implants, made by a company called Poly Implant Prosthese (PIP) which was shut down in 2010, appear to have an unusually high rupture rate and have sparked an investigation in France into possible links to cancer.

Some 300,000 PIP implants, which are used in cosmetic surgery to enhance breast size or replace lost breast tissue, were sold worldwide before PIP went bust last year.

"It's not just France that's concerned. We're looking at 300,000 to 400,000 potential victims in the world," said Alexandra Blachere, the leader of a French PIP implant patient group.

She said women from Italy and Spain had been in touch with her with worries about their implants, and she'd seen reports of problems in Venezuela, Brazil and elsewhere.

Britain's drugs watchdog the Medicines and Healthcare products Regulatory Agency (MHRA) said, however, that there was no reason for patients to be alarmed and stressed as there is currently no scientific evidence to suggest increased health risks.

MHRA officials said they had talked to other health or regulatory experts from France, the Netherlands, Portugal, Italy, Ireland, Hungary, Austria, Denmark and Malta.

"They all agreed that there was no evidence of any increase in incidents of cancer associated with PIP breast implants and no evidence of any disproportionate rupture rates other than in France," it said in a statement.

Founded in 1991, Poly Implants Prosthese was based in southern France and for a while ranked as the world's number three maker of implants, supplying around 100,000 a year.

Some 80 percent were exported abroad, and health authorities around the world said they were watching closely for the results on Friday of an inquiry by France's National Cancer Institute into whether the implants can be linked to cancer.

France has had reports of eight cases of cancer in women with breast implants made by PIP, which is accused of using industrial-grade silicone normally used in anything from computers to cookware.

MHRA said there were also French reports of a woman with PIP implants who died from anaplastic large cell lymphoma, or ALCL -- a rare form of cancer which affects cells from the immune system.

France's drug and medical device regulatory authority, AFSSAPS, ruled last year that the state would pay for the removal of all the PIP implants but only fund replacements for victims of breast cancer, not those who used them for aesthetic purposes.

A French victims association is pushing for the state to pay for replacements for all women with PIP implants.

France's Health Ministry is expected to make an announcement on Friday following the National Cancer Institute's findings.

BRITAIN MONITORING FRENCH DECISION

Australia's healthcare watchdog, the Therapeutic Goods Administration (TGA), said around 8,900 of the PIP implants had been used in Australian women, some of whom had complained about the devices splitting and leaking.

"The TGA has received 45 reports relating to PIP implants, 39 of which relate to rupture," it said in a statement. It has had no reports of ALCL in Australian women with the implants.

The TGA said women with PIP implants should continue to monitor them and consult their surgeons if they have any concerns. Brain's MHRA said the same, adding that it would be "looking carefully at the French safety statement when it comes out as a matter of priority."

PIP was placed into liquidation in March 2010 with losses of 9 million euros after AFSSAPS recalled its implants when surgeons reported abnormally high rupture rates.

During a subsequent inspection of its manufacturing site, officials found PIP had started using a type of silicone gel that was not approved by health authorities, but was around 10 times cheaper.

A subsequent investigation found that a majority of implants made by PIP since 2001 contained the unapproved gel.

A solicitor acting for at least 250 British women taking legal action over their PIP implants said the liquidation of the French company had limited the scope for patients' legal action.

"We're suing about half a dozen clinics that have been involved in implanting the PIP breast implants," Mark Harvey, a partner at legal firm Hugh James, told Reuters.

"We would have preferred to sue PIP, obviously, but they are bankrupt so they have no money and no assets."