International participation at this year's spring carnival is expected to be down due to border restrictions brought about by COVID-19.

Racing Victoria will open quarantine at Werribee for the spring carnival, but currently only to horses on a one-way ticket.

However, that could change if RV gets a request from an overseas trainer wishing to send their own staff to Melbourne to prepare horses for feature races.

Paul Bloodworth, RV's international scout, said the state's controlling body had yet to seek exemption from the Federal Government on restricting non-residents from entering Australia.

Bloodworth said a decision would need to be made by mid-August if international trainers wanted to send horses and staff.

Irish trainer Aidan O'Brien has in recent years sent TJ Comerford and a team of track riders while Godolphin trainer Charlie Appleby has Chris Connett fly out to Australia with a team of stable staff to prepare his team for the spring carnival.

"As it stands, we can get the horses here but the border restrictions that are currently in place in Australia we would not be able to get the staff here," Bloodworth told RSN927.

"We haven't sought any form of exemption from government as it stands, but if their current policies around the border restrictions for non-residents are still in place at the time we need to get the horses and the humans here, that is something we could consider requesting."

Bloodworth said Charlie Fellowes, who prepares dual Melbourne Cup placegetter Prince Of Arran, may consider sending the stayer to Australia and place him in the care of Ciaron Maher and David Eustace if unable to send his staff.

But Bloodworth doubted whether that would be something O'Brien would be prepared to do.

"We'll keep that option on the table if they want to do it," he said.

Bloodworth said Japanese representation this year may prove challenging after their success in the Caulfield Cup and Cox Plate last year.

He said getting flights out of Japan for horses was proving difficult.