A star Vietnamese athlete won the women's 1,500m and the 3,000m steeplechase within half an hour of each other at the Southeast Asian Games on Tuesday, in an imperious display of regional track dominance.

Nguyen Thi Oanh was the reigning gold medallist in both events, as well as the 5,000m -- which she successfully defended a day earlier.

Tuesday's wins give her a total of 11 golds.

At 5:30pm in a hot and humid Phnom Penh, the 27-year-old kicked off with the 1,500m final, winning it in 4:16.850, eight seconds ahead of compatriot Thi Ngan Bui.

That gave her 15 minutes or so to cool down before lining up at 5:50pm for the 3,000m steeplechase.

Even with fresh bodies and minds, the competition could not keep up, Nguyen's time of 10:34.370 putting her six seconds ahead of the Philippines' Joida Gadot Gagnao, who took silver.

"When I knew that I couldn't change the schedule, I accepted it and resolved to conquer the challenge," she told reporters at the track.

"Of course, me and my coaches also prepared the best strategy for me to save as much time and energy as possible for both races," she added, saying she asked to delay her first doping test until after the second race was done.

The runner said she was "very tired, but I'm happy that I finished the races this afternoon".

Though the speed of turnover was new for Nguyen, she has previously won same-day golds, in the 5,000m and 3,000m steeplechase at the 2019 SEA Games.