A man has been seriously injured and three teenagers arrested following a stabbing in Melbourne’s CBD.

There was an altercation at about 3.20am on Saturday at Flinders Street  involving a number of people, police say.

A 21-year-old man was stabbed, suffering serious injuries to his stomach and hands.

Shortly afterwards three teenagers were arrested at Southbank near the Arts Centre.

A 17-year-old from Footscray and two 16-year-olds from Tullamarine and Spotswood are assisting police with inquiries.

Anyone who witnessed the incident or with information about what happened is urged to come forward.

-AAP