The Australian collected gold in the 200m and 400m freestyle at Tokyo's delayed 2021 Games, besting American rival Katie Ledecky, and adding silver in the 800m.

Summer McIntosh has emerged since then, although Titmus reclaimed the 400m world record from the Canadian last year to set up a spicy three-way rivalry in the Paris pool from July.

Compatriot Mollie O'Callaghan edged out Titmus in world record time to win 200m gold at the 2023 world championships, where she became the first woman to win the 100-200m freestyle double.

Titmus, 23, copped a two-month training interruption last year after she had surgery to remove benign tumours from an ovary, discovered by chance when having an MRI scan on a sore hip.

"In the moment, going through the recovery, I was very worried," she told AAP at Wednesday's launch of Australia's aquatic uniforms for the Paris Games.

"I didn't do anything for two-and-half weeks, then had six weeks modified and I was definitely behind where I wanted to be at that point in the season.

"But now I can't think about that; it will just consume my mind and I've done such an incredible job to make up what I missed.

"And I'm training very well at the moment, in good stead for the Games and doing things in training I haven't done before.

"Wearing this suit makes it all feel very real. You really have to earn it and while I've got it on today I'm not in the team yet."

Titmus said her training program complemented all three distances so she was able to hedge her bets.

"Even the 800m - I won a silver in Tokyo - so that race is still a focus as well," she said.

"My favourite is the 400; I feel the most confident racing the 400. It's the race perfectly made for me, but my focus is still evenly split."

Meanwhile two-time Olympic champion cyclist Anna Meares, Australia's chef de mission for Paris, has returned from a reconnaissance tour of Paris earlier this year pleased with the host city's progress.

France this week raised its terror alert to the highest level in the wake of a Moscow concert hall attack that killed at least 130 people.

"From a security perspective it's our highest priority and we're always on the lookout for the changes in security information," she said.

"We trust that the French government and organising committee are putting incredible plans in place to ensure safety not just for the Australian team but spectators and family and friends."

She said athletes will be allowed to leave the security of the Olympic village and will be encouraged to attend the opening ceremony, set to take place on the River Seine in an Olympic first.

"It's open to the athletes and the sports to make that decision," she said.

"If it adds to performance and experience and they're prepared to attend, we'd love to see them."

Australian Associated Press