The Independent on Sunday said its investigation found that Brown has written London's Metropolitan Police, concerned that his phone was compromised while he was chancellor of the exchequer. Brown's staff declined comment.
The paper cited sources saying former Prime Minister Tony Blair had also requested an investigation of possible hacking, but his spokesman denied it Saturday. Other top Labor Party figures are believed to have been spied on too.
The suspected interception of Brown's phone occurred while Andy Coulson was editor of the News of the World. He resigned as Prime Minister David Cameron's director of communications Friday. He denied any knowledge of illegal practices as editor, but said the affair made it "difficult for me to give the 110 per cent needed in this role."
The Conservative Cameron's office denies reports that Coulson's resignation was demanded by Rupert Murdoch, who owns the News of the World, The Independent reported.
The police investigation of the paper is expanding, and Parliament is starting an inquiry into the scandal.