Models with a body mass index (BMI) below a certain level or aged under 16 will be banned from London Fashion Week.

Model will also have to show a health certificate before being allowed on the catwalk.

But Model Health Inquiry, set up by the British Fashion Council (BFC), said that using BMI - a ratio of weight to height - was "not an accurate method of determining health" and could even encourage models to manipulate tests.

Two South American models have died in recent months after suffering from eating disorders, the report said.

Starting this fall, models taking part in London Fashion Week "should provide a medical certificate attesting their good health from doctors with expertise in recognising eating disorders."

The suggestion that teenage models under 16 be banned from London Fashion Week catwalks had "met with strong approval". "The BFC (London Fashion Week's organiser) will implement a ban with immediate effect and ensure that no under 16s appear modelling adult fashion during the September 2007 LFW," Model Health Inquiry added.

London Mayor Ken Livingstone said he would "strongly support" the new measures.

Spain and Italy have already barred models with a BMI of less than 18 from their catwalks.