The NewRun festival, which includes the iconic Hill 2 Harbour race through the city, will not run in 2020 after it was twice postponed due to the coronavirus pandemic rules.

Event director Paul Humphreys said the decision to call off this year's races, due to take place on October 11, came after various attempts to restructure its locations and format to make it COVID-19 safe.

Health orders limit community events to 500 people, a fifth of the expected 2500 runners. Mr Humphreys said it was a combination of postponing twice, an unnecessary workload on police and health authorities, difficulties in securing event areas, increased restrictions on people from outside the Hunter and risks to crew and volunteers that influenced the decision.

Read more: Remember the Hill to Harbour in 2017?

Runners who have already entered can transfer to the 2021 event, scheduled for April 11, take a credit or request a refund.

Those who transfer to 2021 can have this year's bib and medal sent out as a souvenir if they complete their distance and pay postage.

"This has been the hardest decision we have every had to make, but given the unlikely chance that mass gathering numbers will be increased, it became inevitable," Mr Humphreys said. "We know how many people were using the event as a goal, so are asking people to still complete their selected distance and we will send their bib and medal out as a souvenir of their run."

Flashback: All the photos from 2017's Festival of Running

The Hill 2 Harbour began in 2007, morphing into a five-race gathering that usually takes place on the first weekend in April.

Coronavirus rules came into force just two weeks before the original 2020 date.