GMG is now expected to move the sales contract, which covers brands including Smooth and Real Radio, into GCap Media, which has handled sales for GMG's Century stations. However, a move in-house to GMG is also thought to be under consideration.
Sources suggest that the relationship between Global and GMG became strained after GMG wrote to Global to raise concerns over its bid for Emap Radio and to request a guarantee of a large hike in sales revenues.
This week, Global, under the management of its chief executive, Ashley Tabor, and its executive director, Richard Park, also pulled plans to form a joint venture with BSkyB to rebrand LBC News as Sky News Radio and launch it on digital radio next year.
Global has also recently parted company with its ad agency, CHI & Partners, which had created ads for brands including Heart. It appointed The Law Firm to handle the £4 million account last week.