Sports clothing giant Nike has persuaded triple Olympic champion Marion Jones to break off her association with Ben Johnson's former coach Charlie Francis.

Nike is reported to have told Jones that if she does not end her association with Francis plans for a multi-million-dollar advertising campaign centred on her in the lead-up to the 2004 Olympics would be shelved.

Nike pays Jones a basic $800,000 a year to endorse its products and is also the biggest sponsor of USA Track and Field.

I cannot understand why anyone would choose Francis as a coach Michael Johnson

"Things have been laid on the line to Marion," a senior source at the company was reported to have said.

"If she doesn't get out now then it's going to be too late for her and us."

Jones, winner of a record five Olympic medals in Sydney three years ago, had started training with Francis after dropping her long-time coach Trevor Graham last month.

Last week, five-time Olympic gold medallist Michael Johnson said he was puzzled by Jones' decision to work with Francis.

"I cannot understand why anyone would choose Francis as a coach after he admitted he encouraged Ben Johnson to take steroids and his publicly-stated position that no athlete can be successful wihout the use of drugs," said Johnson.

Francis admitted in 1989 that he had encouraged Johnson, stripped of his gold medal at the 1988 Seoul Olympics for doping, and other athletes he coached to use steroids.

His statement last week that he has renounced the use of drugs had failed to take the heat out of the controversy.

Jones's boyfriend Tim Montgomery, the world record holder for 100 metres, has also been training with Francis, but his plans remain unclear.