The 11-strong roster will be cut to nine agencies after a rethink of the geographical areas assigned to the Government department's agencies.
China and Japan have been combined into a single zone, as have West and South Asia. A shortlist of agencies will be drawn up for each zone.
Around 150 agencies are understood to be submitting pitch proposals. The submission deadline is Wednesday this week (5 September). Winners are expected to be decided by October with a view to running campaigns by January - when the existing agency contracts expire.
The key incumbents are TBWA/ISC, which covers Europe, M&C Saatchi for Oceania, Naga DDB for special events and DDB International for meetings and exhibitions.