SE currently uses ten agencies on 14 different contracts, drawn up by geographic area or sector.
The number of contracts and agencies is to be cut substantially, with just four contracts up for grabs.
SE is around 15 months into a five-year organisation-wide restructure that will lead to £200m of cost-savings.
These cuts will impact on the PR budget, which is currently £1.2m per year.
A SE spokeswoman would not comment on the size of future PR spend but confirmed it would be 'considerably' reduced.
The spokeswoman added that one agency could be hired to work on more than one contract, although it is likely four agencies will be hired.
The spokeswoman would not comment on the nature of the remits the agencies would handle, but it is understood the work will be primarily media relations.
The agencies will work closely with SE's core five-strong press office team, which is based in Glasgow.
Among the agencies currently retained are Beattie Media, Weber Shandwick and The Big Partnership.
The pitch process is likely to last until the end of the year, with agencies hired in 2003.
SE is focusing its work around the 'Smart, Successful Scotland' development policy agreed by the Scottish Executive last year. This has three themes: 'growing businesses', 'global connections' and learning and skills.