Mike Powell, 50, admitted at Cardiff Crown Court that he had collected more than 600 indecent pictures of young boys.
Powell, who was mayor of Bridgend from 1984 to 1985, had cut out pictures of boys from magazines and superimposed heads and other parts of the body on them, the court heard.
Jail warning
He pleaded guilty to making indecent pseudo pictures of a child, possessing the pictures, possession with intent to supply and distributing them.
But his sentence was adjourned at Cardiff Crown Court on Monday after police discovered 16,000 more indecent pictures stored on his computer.
Powell, of Highfield Place, Sarn, near Bridgend, was released on bail for two weeks.
Judge David Aubrey QC warned Powell he was facing a lengthy prison sentence.
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