Ofcom will examine a merger between Global Radio and Guardian Media Group Radio, Ministers have announced.
Culture Secretary Jeremy Hunt has issued an intervention notice which requires the watchdog to investigate issues of media plurality that may arise from the merger.
Global Radio, the parent company of brands including Heart, Capital and Classic FM, bought GMG Radio in June.
Mr Hunt said: “On the basis of the information available to me, I have decided that under all the circumstances and, in particular the concentration of ownership which will occur in some parts of the UK, the merger may be relevant to the issue of plurality, particularly in those areas.
“Accordingly, I consider it appropriate to issue an intervention notice in this case, and I am therefore asking Ofcom to prepare a report advising me in greater detail about plurality.”
Ofcom will submit their report to Mr Hunt by 28 September. The Office of Fair Trading will also advise the Culture Secretary on the competition and jurisdictional aspects of the deal by 28 September.
A further announcement will be made once both reports have been considered.