The merger would offer "scope for significant operating cost savings across the combined businesses", a Logica board statement noted.
If the merger, which is now subject to due diligence, goes through, Logica shareholders will end up owning 60% of the new firm and CMG shareholders the remainder
The deal would put the combined group third behind Cap Gemini Ernst & Young and Atos Origin in the European IT services market.
The merger will also allow the company to compete against Nokia and Ericsson in the next-generation multimedia messaging market.
The move intensifies the drive to industry consolidation following the completion last week of IBM's takeover of PwC Consulting, the consulting division of PricewaterhouseCoopers in a £2.2bn deal.
Logica delivered £116m profits before tax for the year to June 2002 on a £1.1bn turnover. CMG posted a pre-tax profit of £40.4m in the year to December 2001 on £920.4m turnover. The combined company would have a market value of around £910m.