Former TVNZ reporter Karl Stefanovic has pulled out of hosting duties on Australia's Today show this morning, amid reports of his marriage breakdown.

Co-host Lisa Wilkinson and Karl's substitute Sylvia Jeffreys briefly referenced his absence at the top of the show, with Lisa claiming he was off doing "a 60 Minutes tidy up".

She added: "He had a couple of loose ends on a story he's finishing, so he'll be back in the chair tomorrow."

Karl and Cassandra with their three children - Jackson, Ava and River. Photo / News Limited
Karl and Cassandra with their three children - Jackson, Ava and River. Photo / News Limited

According to The Sunday Telegraph, the Today presenter is understood to have moved out of the home he shares with wife Cassandra Thorburn and their three children, and is believed to be staying at his close mate James Packer's Bondi apartment.

Advertisement also understands Stefanovic was scheduled to host an event in the city last night, but pulled out at the last minute.

Despite news of the alleged split being widely reported across media outlets over the weekend, the 42-year-old showed no signs of any strain while hosting Today on Monday.

Stefanovic has been vocal about how supportive his wife has been of his work, claiming she gave up a successful career at the ABC to raise their three children.

The separation has reportedly come as a major shock to the couple's friends and family, although it's understood Stefanovic and Thorburn are trying to repair their relationship.

While Stefanovic was manning the Today show desk yesterday, Thorburn was spotted stepping out to do the daily school run for the couple's three children - Jackson, 16, Ava, 11 and River, 10.

Stefanovic began his career in New Zealand as a reporter for One News. He made global headlines in 2014 when he revealed he had been wearing the same suit every day for a year.