Joseph Gordon-Levitt has shared a message of support to the graduating classes of 2020.

The 'Knives Out' actor has urged young people who have had their final school years ended early because of the coronavirus pandemic to ''rise to the occasion'' and hailed them as the start of a ''new generation'' who will be asked to ''rebuild the world'' in the years to come.

He wrote in an open letter on Twitter: ''You've been handed a challenge you didn't ask for. And now it's on you to rise to the occasion. Everyone alive today will remember the world before and after this pandemic, and you're the ones graduation right when it began. For better or worse, you're the start of a new generation...

''You're the ones who are gonna rebuild the world in the wake of this crisis.

''Safer, healthier, stronger, more fair, and more beautiful than it was before.''

The 39-year-old star sympathised with those missing out on their graduation ceremonies but admitted the students have ''bigger things'' to worry about.

He wrote: ''I know it sucks you didn't get to wear a cap and gown and walk the stage and share the moment with your friends and families in person. I know it sucks, because I actually didn't get to either...but here's the hard, shitty truth... you have bigger things to worry about.''

Joseph has also started an initiative urging the class of 2020 to write their own reflections, or for others to send messages of support to them.

He tweeted: ''Write a letter to the class of 2020. If you're graduating this year, or you're a teacher, or you're somebody who just wants to share your wishes for these young people becoming grown-ups in this f***ed up moment, I want you to be part of this project:''