Tequila\London inherited the Unicef account when it merged with its sister agency TBWA\GGT in January. The review is part of a statutory process held every four years.
TBWA\GGT won the brief in 2001, after a four-way pitch against Proximity, Lowe Live and the previous incumbent, Carlson.
The UK review is being conducted by Allan Freeman, the former managing director of WWAV Rapp Collins West, who is now a freelance consultant. He is thought to be drawing up a longlist of eight agencies.
Credentials meetings will take place ahead of a pitch between the shortlisted agencies next month.
Unicef UK is one of 37 national committees that make up the United Nations Children's Fund. Last week, Unicef began a search for a global direct marketing agency to create a campaign to help children affected by Aids.
Its Geneva HQ is in the process of hiring an agency across Europe to support its Asian tsunami relief work.
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