Suits, Phelps's events will be focus at US Nationals

The spotlight will be on what swimmers are wearing as much as Beijing Olympics multi-gold winner Michael Phelps at the US championships next week.

More than 100 world records have been broken in the past 18 months, the latest on Wednesday when Spain's Aschwin Wildeboer Faber broke the 100 metres backstroke world record at the Mediterranean Games, by swimmers in high-tech suits.

FINA approved a list of suits last month that can be used in competition, though there are concerns they may not have gone far enough.

"I don't think there is any doubt some of the world records that have been broken over the last two years are due to the athletes and some of the world records are more due to the suits," US national team head coach Mark Schubert told reporters.

The national championships, which begin at the Indiana University Natatorium main pool next Tuesday, are doubling as trials for the world championships in Rome.

Veteran Dara Torres, winner of three silver medals in Beijing, is among a group of swimmers expected to keep their suit options open next week.

The 42-year-old five-time Olympian had been expected to retire after Beijing but decided to return to the pool in a bid to swim in her second world championships.

"I really thought I was done after Beijing," said Torres. "I have a sort of love-hate relationship with swimming and after the Olympics I was kind of ready to move on but I wasn't burned out. "

While the suits may continue to be an issue, attention will be focussed on Phelps, who won a record breaking haul of eight gold medals at the Beijing Olympics, but has been experimenting with new, and shorter, events.

He is expected to swim the 100 and 200 freestyle and 100 and 200 butterfly at the nationals.