Earlier this week, the world governing body announced a ban but said it might not come into effect until April or May.

That has now changed.

Cornel Marculescu, FINA's executive director, said: "Now, without a doubt, the rules are applying January 1, 2010.

"The manufacturers are ready and can begin [suit] submissions November 1 or before."

Phelps, winner of a record eight Olympic gold medals in Beijing last year, said: "It's going to be cool come January 1 to be able to have all of us pretty much wearing the same suit.

"All of this is going to be finished and then we're going to be able to talk about swimming again, not suits."

Phelps' coach Bob Bowman had threatened to withdraw the American swimmer, whose eight victories in the Chinese capital took his career total to 14 Olympic gold medals, making him the most successful in history, after he was beaten by unheralded Paul Biedermann of Germany in the 200 metres freestyle on Tuesday.

Biedermann wore a 100 per cent polyurethane Arena suit, while Phelps stuck with last year's Speedo LZR Racer, which is less than half polyurethane.

This year suits from Italian manufacturers Arena and Jaked are considered faster.

Last year, Phelps and others wearing the LZR profited from its increased speed.

Under the new rules, it, as well as the Arena and Jaked suits will be banned.

Men will be restricted to suits that extend from the waist to the top of the knees; women's suits cannot go past the shoulders or beyond the knees.

Bowman said: "I'm just thrilled that they did it, because it's the right thing to do.

"We know they want to do the right thing for the sport, they just need to do it, so I'm glad to hear it and so is Michael.

"We'll probably keep our competition schedule.

"There will be some little questions about what suit is he going to wear until the end of the year, but they're minor.

"In training I don't care."

FINA plans to issue new suit guidelines to manufacturers by September 30 and thought about delaying implementation for a few months to give the companies enough time to produce new suits.

With two days still to go, 35 world records have been set at these World Championships, five more than at the last edition two years ago in Melbourne.

So far the only swimmers to set world records at the Championships who have not been wearing a polyurethane suit are Phelps, Ryan Lochte and Britain's Gemma Spofforth (pictured), who have all competed in the Speedo LZR Racer.

FINA also announced a rule requiring suits to be approved one year before Olympics or World Championships, and available commercially six months in advance.

A scientific commission with materials experts from each continent will approve swimsuits and monitor developments in technology, FINA said.

USA Swimming is considering installing the new suit rules for domestic competition before the end of the year.

Polyurethane bodysuits will be banned for a "Duel in the Pool" competition in Manchester in December, with the United States facing an all-star team from France, Russia and Britain.

USA Swimming executive director Chuck Wielgus said: "We met after prelims this morning and agreed to adopt the rules for that meet.

"Whether or not USA Swimming adopts those rules any sooner is something we'll talk about when we get home."