SINGAPORE - The 30-year-old man who was rescued by Australian lifesavers, including a father-and-son duo, after he was swept out to sea near the Twelve Apostles is not a Singaporean, The Straits Times understands.

Mr Ross Powell, 71, and his son Andrew, 32, died on Sunday (April 21) after their life-saving boat overturned in the surf while rescuing the man.

The man had been wading at the mouth Sherbrook River at Port Campbell when he got into trouble.

While the man's nationality and name were not officially released by local authorities, a few Australian and international news outlets, such as 7News Melbourne, The Sydney Morning Herald and DailyMail UK, reported that he was a Singaporean tourist.

However, ST understands that the man is not a Singaporean.

Earlier reports by other news websites had also suggested the man was taking photographs when he was swept off a rock at the mouth of the river, but emergency services later refuted this.

The Twelve Apostles, which is a popular attraction among tourists to Australia, are a series of massive limestone stacks situated off the Victoria state coast.

The Powells were hailed as heroes after news of their deaths broke.

Australian Prime Minister Scott Morrison said in a tweet on Monday: "Surf lifesavers are selfless & brave. We thank them all for their service & extend our deepest sympathies to Ross & Andrew's family & friends."

Ms Amber Griffiths, the partner of Andrew and who local media reported was pregnant with their second child, wrote about her heartbreak on Facebook.

"Today we lost two of the most beautiful people to ever exist - always putting others first," she wrote.

"The love of my life, light of my life, father of my baby girl. My heart is broken. I miss you Andrew Powell."

The man who was swept out to sea suffered hypothermia and was treated at the Warrnambool Base hospital. He was discharged on Monday.