Following the news, the shares jumped a further 21p, to close at 107p.
Reg Bolton, company finance director, refused to name the interested buyer, but said the approach had been unsolicited. He stressed that an offer "may or may not be forthcoming."
Analysts speculated that a bid might come from competing food concerns, including Northern Foods, Geest, McCains or Heinz.
Canadian Pizza, which came to the market late in 1993, has had a rocky ride of late, losing a large share of its contracts to supply pizza bases and toppings to large retailers within months of coming to market. One of these is believed to have been Sainsbury.
Last month, it announced three new contracts with retailers, and although it again refused to specify the names, it is believed that Tesco is the largest of the three.
Analysts said the new contracts should boost performance in the second half of the year. In 1994, the company earned pounds 2.3m, on turnover of pounds 15.6m, down from pre-tax profits in 1993 of pounds 3.2m. In the first six months of 1995, earnings dropped to pounds 600,000.
Canadian Pizza supplies retailers and catering outlets in Britain and overseas, including Netherlands, France, Spain and Australia.
Mr Bolton said the company made its announcement about a possible bid on the advice of advisers, and was not asked to comment by the Stock Exchange.
"We don't know why there was a share movement, but we were advised that we should make a statement if the rise continued," he said.
Mr Bolton confirmed that the talks with the unnamed buyer would continue on Monday.