The editor-in-chief of News Corp’s national masthead The Australian will step down from his position after four years to deal with a health issue.

Chris Dore, who has edited The Courier-Mail and The Daily Telegraph, took the helm of the national masthead in 2018 after its former editor-in-chief, Paul Whittaker, was promoted as chief executive of Sky News.

News Corp executive chairman Michael Miller said in a note to staff Dore was undergoing surgery this week. The paper will be led by editor Michelle Gunn, who was appointed in May 2020.

In a note to staff, Dore said he was “exhausted”.

“Any editor will admit the past few years have felt like dog years and as you know, I have no off-switch,” Dore said. “I am exhausted, and have recognised I can’t keep going on like this. I have long-standing personal issues I need to resolve and am leaving News to concentrate on restoring my health.”

Dore began his career at News Corp as a copy kid more than 30 years ago. He has worked across Australia and led tabloids The Daily Telegraph and The Courier-Mail as well as The Sunday Times in Perth, when it was owned by News Corp. Media sources said Dore has not been seen in the office for weeks, with staff told he was in the US.

Miller said the company wished him the best with his surgery.

“I have asked Michelle Gunn to continue to edit The Australian,” he said. “Over three decades in senior roles at The Australian, Michelle has developed an insightful understanding of The Australian’s audience and the issues and debates that interset them, most which are at the heart of the nation’s future.”

News Corp declined to comment further on the matter.