BELGRADE, Serbia -- The head of Serbia's state lottery resigned on Thursday following allegations of fraud during a live ticket draw this week.

In a live broadcast Tuesday evening, one of the numbers in the winning combination appeared on TV screens before it was actually drawn. That sparked accusations that the numbers had been chosen in advance.

The State Lottery has denied fraud and blamed the incident on a "technical mistake." The company head, Aleksandar Vulovic, said Thursday that he was stepping down out of "moral obligation."

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

Police said lottery employees who worked during the draw will undergo a lie detector test, while computers and other equipment have been impounded. Police said they have questioned six people in the scandal.

The lottery is very popular in Serbia, a Balkan country with a poor economy and widespread corruption.