The chaos over the controversial "supersuits" that has engulfed swimming yesterday continued as Michael Phelps suffered his first defeat in five years in the 200m freestyle just after the world governing body announced it would ban the costumes.

Britain's Gemma Spofforth won gold at the world championships in the women's 100m backstroke, setting a world record in the process, but the defeat of Phelps sent shockwaves through the sport and his coach, Bob Bowman, said the American would not swim again until the issue was resolved. "Bob sorts my schedule," confirmed a distraught Phelps. Both Phelps and Spofforth were wearing Speedo LZR suits, which are being superceded by the new generation of wetsuit-style costumes made by adidas, Arena and others. From next year all will become illegal but Phelps was beaten by Paul Biedermann, a German wearing an Arena X-glide suit. Bowman said that Fina had better "do something or they're going to lose their guy who fills these seats."

The new regulations announced yesterday will limit the size of the suits and restrict the materials from which they are made to "textiles". There are numerous difficulties with the decision. First, Fina, the sport's governing body, cannot say when these changes will occur, their heavily-qualified estimate being "by April 2010". And secondly, Fina has yet to reveal what the term "textiles" actually means. Additionally, the rule change is in effect only a bye-law, which means the decision can be reversed at any point.

Fina insists that will not happen but it has already banned the new generation of swimsuits once this year only to change its mind after coming under heavy pressure from manufacturers and sponsors. Controversially, the records set in the new suits will stand. Fifteen world records have been set so far in Rome but not all in the new generation of suits. "Remember," said Fina's executive director Cornel Marculescu last night, "the world records are being broken here because these people are fantastic athletes."

Tell that to Michael Phelps. The greatest Olympian swimmer in history with 14 golds was not just beaten in the 200m, he was thrashed. Biedermann shattered Phelps' world mark of 1min 42. 96sec with a time of 1min 42sec. Phelps said: "I look forward to racing Biedermann next summer. It will be fun when swimming gets back to swimming." Of his race, done in a time of 1:43.22, Phelps added: "Theoretically it was a pretty good swim for me. Three tenths off my best time after taking six months off. I'm not happy but I know I didn't train much this year."Biedermann was understandably ecstatic, saying: "It's still hard for me to believe that I defeated a legend like Phelps. It is true that he has been training only for six months and he is not the same as at the Beijing Olympics. But the German team which I am part of is great." Biedermann finished a distant fifth behind Phelps in the 200m final in Beijing. Ten months on he trimmed four full seconds from his time.

The technology has moved on so quickly that Phelps' Speedo LZR seems almost obsolete. Or it did until the very next race, when Spofforth broke the world record by 0.36 of a second with a time of 58.12sec. It was the first gold won by a swimmer in a Speedo suit in Rome. The LZR is only partially polyurethane, whereas the new suits are fully coated with the material. That makes them water-impermeable, adding a huge amount of buoyancy.

He may well stay that way too, because Fina's announcement has taken back the technology used in swimming by a full decade. Marculescu insisted the sport was "evolving" but in truth it is a regression. With the new restrictions in place it will be a long time before anyone swims as fast as many have at these championships.