LONDON — A day after presiding over the publication of his new, damn-the-critics Sun on Sunday tabloid, Rupert Murdoch was confronted with fresh allegations from a top police investigator that the daily Sun had systematically paid large sums of money to “a network of corrupted officials” in the British police, military and government.

The allegations, part of a deepening criminal probe into The Sun and Mr. Murdoch’s defunct News of the World, highlight the challenges to Mr. Murdoch and his News Corporation as he seeks to minimize the threat to his British media holdings. They also cast a harsh spotlight on the freewheeling pay-for-information culture of the British media.

In public testimony on Monday, Deputy Assistant Commissioner Sue Akers, who is leading the criminal investigation into Mr. Murdoch’s newspapers, said The Sun, long a source of special pride and attention for Mr. Murdoch, had illegally paid the unidentified officials hundreds of thousands of dollars in exchange for news tips and “salacious gossip.” She said the payments had been authorized “at a very senior level within the newspaper.”

Her comments, unusual during a continuing criminal inquiry, directly undercut Mr. Murdoch’s campaign of support for the embattled newspaper. On Feb. 17, the 80-year-old Mr. Murdoch made a grand entrance into the Sun newsroom, where, marching around in shirtsleeves, he vowed to reinstate journalists suspended in the criminal investigation, offered to pay their legal bills, issued a robust statement about the paper’s probity and announced that he was defying conventional industry wisdom by starting a Sunday issue.