BEIJING (AFP) - Olympic champion Liu Zige demolished the women's 200m butterfly world record at China's National Games on Wednesday, shaving almost two seconds off the previous mark.

The official Xinhua news agency said Liu touched in 2:01.81, shattering Australian Jessica Schipper's record of 2:03.41 set at the world championships in Rome in July. Related article: Chronology of 200m butterfly records.

Liu, who won Olympic gold in a world record time in Beijing last year, finished almost four seconds clear of her long-time arch rival Jiao Liuyang, runner-up at the Olympics.

The 22-year-old warned she could improve on Wednesday's time.

"I don't think the result today is fast enough for me, and there is still room for me to better the record in the future," she was quoted as saying.

"Every tiny progress could make a new world record, which is very common in the pool.

"My performance was satisfactory but not extraordinary compared with that of my 100m butterfly final."

In the 100m butterfly on Sunday, Liu clocked 56.07 seconds to break the Asian record set by Jiao in Rome.

Her world record on Wednesday was the first in the pool at the National Games in Jinan, in eastern Shandong province, with Liu attributing her success to her tough training regime after the worlds, where she finished second.

"I trained very hard after I came back from the Rome worlds, without even one day off," said Liu, who led the race from start to finish.

"I cooperate very well with my coach, who set a higher standard for my training in terms of intensity and capacity."

Liu's mentor, Jin Wei, said before the race that he felt she could break Schipper's world record after watching his star pupil mature following a training stint ahead of the Olympics under famed Australian coach Ken Wood.

Despite once again losing out to Liu, Jiao was gracious in defeat.

"I'm really happy for her as she created a historical record for China. She was in her best shape for competition, better than mine," she said.

"Both of us are very young, and we have many chances to race. We will train hard to achieve better results for our country."