In a statement issued on Friday morning, Morrison said that he would return to Australia as soon as can be arranged.

The PM has received criticism for going on an overseas holiday with his family, reportedly to Hawaii, while much of his home state of New South Wales (NSW) was ablaze.

Protesters on Thursday gathered outside Kirribilli House in Sydney, the residence of the PM, to demand Morrison take greater action against climate change, according to the local media Special Broadcasting Service's (SBS) report.

Prime Ministers have traditionally taken time off in January but Morrison said he brought his holiday forward because of planned official visits to Japan and India in January.

"I deeply regret any offence caused to any of the many Australians affected by the terrible bushfires by my taking leave with family at this time," he said on Friday.

"I have been receiving regular updates on the bushfires disaster as well as the status of the search for and treatment of the victims of the White Island tragedy."

In a separate statement, Morrison expressed "sincere condolences and sympathies" to the families of two volunteer firefighters who died on Thursday in a vehicle accident, confirmed by the NSW Rural Fire Service.

"Our hearts go out to their families, friends and colleagues who have been working tirelessly beside them, particularly during this Christmas period," Morrison said.

"Given these most recent tragic events, I will be returning to Sydney from leave as soon as can be arranged."