WCRS, which has struggled creatively with its biggest account for some time, has declined the opportunity to repitch for the business.
The decision to review the account came as Camelot announced the appointment of Abbott Mead Vickers BBDO to produce the £4 million launch campaign for EuroMillions, Camelot's new European lottery due to launch next year with a £35 million jackpot.
AMV beat the incumbent, WCRS, in a head-to-head shootout after the early contender Publicis was dropped from the pitch. Camelot called on the AAR to help finalise its shortlist.
The UK review will not affect AMV's hold on the EuroMillions business and the agency has now been asked to pitch for the larger account.
A Camelot spokesman said no decision had yet been made on whether an outside consultant would be used to draw up a list of agencies.
Phil Smith, the commercial director at Camelot, said: "We have been working closely with WCRS for five years. We have a duty to make sure we have the best advertising strategy in place and we look to review our commercial relationships on a regular basis.
"We are one of the most efficient lottery operators in the world and we are keen to remain that way. The decision to appoint AMV to EuroMillions gave us the opportunity to look more broadly.
"We are finalising pitch deadlines as we speak and hope to make a decision in the early part of the New Year."
The review will be run by a team comprising the Camelot chief executive, Dianne Thompson, Smith, the director of marketing and communications, Jo Kenrick, and the player marketing controller, Nicole Louis. Louis was Orange's head of brand communications when it reviewed out of WCRS in 2000.
In January, WCRS dropped the comedian Billy Connolly and the "don't live a little, live a lotto" campaign. It was replaced with a £20 million campaign focusing on the good that lottery money does around the country.
Stephen Woodford, the WCRS chief executive, said: "This is a sad outcome for five years of hard work. However, the needs of our 18 other clients must come before our natural instinct to try to repair a relationship in the heat of a pitch."
Camelot has suffered a rocky financial performance over the past few years. However, this year the lottery operator has managed to stabilise its ticket sales. Sales for the second quarter of this financial year, July to September, were £1.1 billion, matching sales for the previous two quarters.
Media planning and buying held by Media Planning Group and OMD, will not be affected by the review.