A woman has sustained burns to her face and arms after a basketball exploded in her hands at a Melbourne beach.

Police said the 21-year-old victim had been walking along Black Rock beach, near Half Moon Bay, with a 37-year-old man at about 10.40pm on March 17 when she walked ahead and saw a basketball in the sand.

As she picked up the ball, it exploded in her arms, burning her face, head and forearms, police said.

She immediately ran to the water in an attempt to cool down the burns to her upper body before paramedics arrived at the scene.

She was rushed to the Alfred Hospital in a stable condition.

Detectives from the Arson and Explosives Squad investigating the incident believe sparklers were attached to the ball.

Witnesses told police the basketball was rolled onto the beach “towards the woman” by a group of people who soon after walked away.

Police located the exploded basketball at the scene.

“At this time the reason for the explosion is unknown and police are not sure whether the group had intended for anyone to pick up the ball or why the group had it at the beach,” a police spokeswoman said in a statement.

Anyone with information about the explosion has been urged to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report to www.crimestoppersvic.com.au