The news is a blow to TBWA, which is currently defending its £22m Abbey account. TBWA is not repitching for the account.
The tabloid newspaper owner, which spends £13m on The Sun and £7m on the News of the World, is using the AAR to approach agencies.
The review comes as the latest newspaper ABC figures are published today, which brought bad news for News Group Newspapers.
The Sun was down 3.23% to 3,273,116 while Trinity Mirror rival the Daily Mirror was down 1.63% to 1,719,743. Year-on-year, The Mirror is down 8.86% while The Sun is only down 3.73%.
The News of the World was down by 4.55% to 3,649,466 as the Sunday red-top market was hard hit. The Sunday Mirror was down by a whopping 7.12% to 1,534,736.
The advertising review follows the appointment of Roland Agambar as marketing director of News Group Newspapers last October. He will be leading the pitch.
TBWA has held the News Group account for 10 years, adopting it from Simons Palmer, which won the business in 1993.
Andrew McGuinness, chief executive of TBWA, said: "We've had a great run with News International. They've been a fantastic client and we've learnt a lot from them. We're looking forward to using that knowledge elsewhere."
The review is not thought to affect Carat, the publisher's media agency.
News Group was not available for comment.
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