American Jessica Hardy kept the world records flowing when she broke the women's 50 metres breaststroke mark at the world short-course championships on Thursday.

Hardy, who won the world long-course title in 2007, clocked 29.58 seconds to beat the 29.90 world short-course mark set by Australia's Jade Edmistone in Brisbane in 2004. It took the world record tally to four after three had tumbled on Wednesday's opening night.

The 21-year-old American seized control from the start and finished more than half a second ahead of her nearest pursuer, Yuliya Efimova of Russia.

Efimova, who won the European 200 breaststroke title last month, clocked 30.22 but to no avail as she was disqualified for a premature start.

Silver was shared by Britain's Kate Haywood and Australia's Sarah Katsoulis who both touched in 30.35. Edmistone finished fifth, losing both the title she won in 2006 and the world record.

"I knew I felt good. I was hoping (for the world record) but I didn't expect it," Hardy said.

"I wasn't rested at all for this because we've got our Olympic trials coming up. It's only a couple of months away. I'm working so hard and I'm feeling so strong."

Ryan Lochte had already claimed gold for the US in the evening session by retaining his 400 individual medley title with a fluent victory.

Lochte, who won three titles at the 2006 world short-course championships, always looked in control and although fellow American Robert Margalis and Ioannis Drymonakos of Greece were in close contention as they moved on to the concluding freestyle leg, he collected the gold in four minutes 3.21 seconds.

Margalis, the 2003 Pan-American champion, took silver in 4:03.74 and Drymonakos, the European silver medallist, bronze in 4:05.11.

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