Another sporting event has fallen under the weight of COVID 19, the Port Macquarie Ironman has been cancelled for 20-21.

Unfortunately, the recent extension to the lockdown in Greater Sydney announced on 14 July has had, and will continue to have, a significant impact on our ability to prepare and deliver this event, and the health and safety of competitors, staff, volunteers and the regional community is, as always, of the utmost importance.

The 35th anniversary was due to return to Port Macquarie on September 5 after being postponed three previous times due to COVID-19 and floods.

But current restrictions, public health orders and lockdowns surrounding Greater Sydney and Melbourne have forced their hand.

Ironman Australia regional director, Chris Jarvis admitted it was frustrating and disappointing although in the end they were left with little choice.

"We've only got two weeks left until we're meant to come out of lockdown and now there's no runway left to land the plane," Mr Jarvis said.

"We've never had a clear runway and we also need to coordinate a whole community to be registered to this event.

"It's definitely frustrating; this is our fourth attempt at staging the 35th anniversary. We're not calling it a birthday, we're going to stay at 34 years old."

With 60 per cent of competitors travelling from around NSW - and the majority from Greater Sydney - organisers were already keeping a close eye on the ever-changing public health advice.

Constant changing of health advice made it impossible for Ironman Australia to keep up to speed with a "current rule book" which was required to run a COVID-safe event.

"Without a doubt the call needed to be made now," Mr Jarvis said.

"We're running the gauntlet because these events take months to plan and we've already had four evolutions.

"This event brings in new people and the new money that is brought into the town supports the community.

"It makes that community shine, so we couldn't guarantee we could coordinate and deliver the event to those people.