Producers of this year's Academy Awards have sent a letter to nominees telling them that they cannot appear virtually and that casual clothes "are really not" allowed. 

The 93rd Academy Awards are set to take place next month, with an in-person event at Union Station in downtown Los Angeles.

There will also be some live elements from the ceremony’s usual home at the Dolby Theatre in Hollywood.

In a letter sent to nominees and published by US outlet Deadline, producers said a virtual appearance is not allowed and the Academy will accept awards on behalf of any winner unable to make the show.

The letter states: "For those of you unable to attend because of scheduling or continued uneasiness about traveling, we want you to know there will not be an option to Zoom in for the show.

"We are going to great lengths to provide a safe and ENJOYABLE evening for all of you in person, as well as for all the millions of film fans around the world, and we feel the virtual thing will diminish those efforts."

The Academy, the body which oversees the Oscars, said the ceremony will be "intimate" and promised it would be done safely under pandemic-era precautions.

The letter, from producers of the show Steven Soderbergh, Stacey Sher and Jesse Collins, says: "We are treating the event as an active movie set, with specially designed testing cadences to ensure up-to-the-minute results, including an on-site Covid safety team with PCR testing capability.

"There will be specific instructions for those of you travelling in from outside of Los Angeles, and other instructions for those of you who are already based in Los Angeles. This will all come directly to you from the Academy to ensure you have a safe, carefree evening (a glimpse of the future?)"

Recent awards shows have seen some nominees deciding to dress casually for the big night, with actor Jason Sudeikis making headlines for wearing a hoodie while appearing virtually at the Golden Globes.

Such a laidback approach will not be welcome at the Oscars, the Academy said.

Of the dress code, the letter said: "We’re aiming for a fusion of Inspirational and Aspirational, which in actual words means formal is totally cool if you want to go there, but casual is really not."

Producers stressed the importance of "stories" to the nominees and said each one of them will be interviewed to "help us tell the story of your path" to the ceremony.

They added: "We want to highlight the connections between all of us who work in the movies and show that the process is uniquely intimate, collaborative, and fun (Usually. Hopefully?)."

Oscar nominees were announced this week and Irish animated feature film Wolfwalkers will compete with Soul, Onward, Over The Moon and A Shaun The Sheep Movie: Farmageddon for a golden statue.