Australian race walker Jemima Montag has claimed her third consecutive national title in the 20km walk, smashing the national record by 10 seconds.

The Tokyo Olympian eclipsed Jane Saville's record set in 2004, with a stunning performance at the Oceania and Australian 20km Race Walking Championships in Adelaide on Sunday.

Montag clocked 1 hour, 27.34 seconds — 10 seconds faster than Saville's previous benchmark and more than four minutes ahead of her Tokyo Olympics teammate Rebecca Henderson (1:31:44).

The 23-year-old, who finished sixth in last year's Olympic 20km final, claimed her third consecutive national title and also secured selection for the World Athletics Championships in Oregon this July.

"It feels surreal at the moment," Montag said.

"That national record is something I have been thinking about for a few years but we've had the pandemic and cancelled races.

"It wasn't what I had in mind, but I could feel it was on in the first 5 kilometres."

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Montag's feat came amid urging from her coach Brent Vallance which almost upset her concentration.

"Sometimes you have that fear of success where your coach is yelling out that the record is on today, which is scary because you have the feeling of not wanting to let anyone down," she said.

"It feels exciting to lock that spot in for Oregon, qualifying early, and now we've got the next four or five months to put our heads down and train smart.

"I've started an intense medical post-graduate course, so being efficient with times and qualifying is important. It feels good to do the three-peat, and to have so many of the emerging senior boys to walk with was really lucky."

In the men's 20km walk, prodigious talent Declan Tingay captured his maiden national title with a time of 1:20:44, which also earned him selection for the world championships.

Tingay, who placed 17th in the event at the Tokyo Olympics, finished over three minutes ahead of Kyle Swan (1:21:39).

The championships also featured 10km and 5km events for the country's emerging talent.

Olivia Sandery, coached by Australia's most decorated track-and-field athlete Jared Tallent, took out the women's 10km race in 46 minutes and 35 seconds, just behind the men's 10km winner Marcus Wakin (45:56). Both results have secured them qualification for the World Under-20 Championships.

AAP/ABC