The fresh criticism comes amid a revelation Coulson was still being paid by the newspaper group for at least five months while serving as the Conservative Party's director of communications at a reported salary of $450,000 a year, The Daily Telegraph reported Tuesday. News International provided private healthcare benefits for Coulson for three years and allowed him to keep his company car after he left the company, the BBC reported.
"David Cameron now faces allegations that one of his top advisers was also in the pay of News International," a Labor Party spokesman said. "The prime minister needs to immediately make clear whether these allegations are true."
Coulson resigned from the News of the World after Clive Goodman, the former royal editor at the paper, was jailed for illegally intercepting voicemail messages, and took up the Conservative Party post in July 2007.
Conservative Party sources insisted they had no knowledge of any News International payments made to Coulson, The Guardian reported.
News International -- owned by Rupert Murdoch's News Corp. conglomerate -- had no comment.
"News International consistently does not comment on the financial arrangements of any individual," a spokesman said.