The merger of the world's two largest beer manufacturers "represents a major threat to global health, to which researchers, funders and regulators must respond more effectively," warn global health experts in The BMJ this week.

Of particular concern are the health implications for the growing epidemic of alcohol related harm across low and middle income countries, they say.

Last month, it was announced that Belgium based Anheuser-Busch InBev (AB InBev) and London based SABMiller have agreed in principle to merge.

At around £70bn (€100bn; $106bn) this would be the third largest deal in corporate history, and the new company will produce an estimated one third of all beer sold worldwide, explain Professor Jeff Collin and colleagues at the University of Edinburgh.

Importantly for global health, the merger is driven by prospects for expansion in developing countries, with a particular emphasis on Africa as "a critical driver of growth for the combined company."

The health implications of this forecast are disturbing, they say. Market growth on this scale is predicated on "exploiting Africa's low per capita consumption of beer," targeting low income consumers to drive increased sales.

This expansive trajectory also "echoes that of transnational tobacco companies, with which the alcohol industry shares strategic similarities and has close corporate links as well as comparable health effects," they add.

Yet whereas regulation underpins efforts to control transnational tobacco companies, the authors point out that the global alcohol industry "continues to occupy an ambiguous space in which an indirect acknowledgement of serious health effects coexists with the prospect of partnerships and shared objectives."

For example, WHO's emerging framework for engagement with non-state actors, "precludes partnership with the tobacco and arms industries but makes no specific reference to alcohol."

They believe the new sustainable development goals provide opportunities to respond to this threat. And they urge public health to "do more to ensure that conflict of interest with alcohol companies is recognised and addressed."