The head of Serbia's state lottery has announced his resignation following allegations of fixing televised draws.

During a live television broadcast, one number in the winning combination appeared in an on-screen graphic before it was drawn for the pot.

The lottery insists it was a 'technical mistake,' but Aleksandar Vulovic says he has a 'moral obligation' to resign.

"The draw was completely in accordance with the rules and the company abides by the law," the state lottery said in a statement.

Police have begun an investigation - with six people already questioned and a number of computers seized. A statement from police said all employees who worked during the draw will be given a lie-detector test.