The trials, due to take place between June 18 and 27, are the first major event to be held at the revamped $270 million (£194 million/€223 million) Hayward Field track and field facility at the University of Oregon, which has undergone a major facelift in time for the World Athletics Championships.

The World Championships were originally due to take place for the first time in the US this year but have now been pushed back to 2022 due to the Olympic Games in Tokyo being rearranged.

"Based on state and local health regulations for stadium capacity and the high volume of tickets that already have been sold, the LOC (Local Organising Committee) has determined that the tickets held by existing customers cannot be fulfilled," TrackTown USA said in a statement.

"As a result, all ticket customers will have their tickets refunded.

"A revised ticketing programme with an updated seat inventory that is compliant with new regulations will be announced in May."

There had been strong interest in attending the trials, always one of the most high-quality athletics events of the year, especially with the opportunity to take in the renovations at Hayward Field.

The number of fans permitted to attend the Olympic Trials has yet to be announced but it is expected to be a fraction of the 12,650 permanent seats at Hayward Field.

Athletes, officials, coaches, media and stadium personnel, such as concession workers and cleaning staff, are expected to be included in the capacity calculation, leaving fewer spots for spectators each day.

Oregon recently changed its regulations to allow spectators at sporting events, but those regulations specify limitations on stadium capacity based on the county’s risk level.

Last week the Oregon Health Authority recorded nearly 1,000 new daily coronavirus cases - the biggest spike since mid-January.

Additionally, social distancing will be required in the seating bowl.

Athletes' families will have the opportunity to purchase tickets before the general public.

"Demand for tickets to the Olympic trials continues to be at an all-time high and we are confident that some number of spectators will be able to attend the event if regulations allow. Unfortunately, we now know that we won’t be able to both comply with important public health regulations and fulfil the tickets that already have been sold," said TrackTown USA chief executive Michael Reilly.

"We have considered numerous alternatives and have determined that taking this action now is in the best interest of our customers.

"By starting over with an updated seat map and policies that account for new regulations, we are providing the public with the opportunity to make purchasing decisions based on information that is very different from when tickets were originally on sale."