Arlene Foster and Jonathan Bell in happier times.

The Strangford MLA was suspended from the DUP a month ago after he spoke out in a televised interview with Stephen Nolan where he made allegations about the party and the closure of the RHI scheme.

In an televised interview broadcast immediately after Mr Bell’s comments, DUP leader Arlene Foster made a series of allegations about her party colleague.

There was speculation at the time that Mr Bell may be considering legal action after he directed journalistic questions to the libel lawyer Paul Tweed.

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Now it has been confirmed that Mr Bell has taken the first step towards launching a legal action – although it does not appear that he has as yet issued a writ.

When asked about the situation, Mr Tweed said that he was not in a position to make any comment at this stage other than to “confirm that it is correct that Arlene Foster and Christopher Stalford have been put on notice in relation to comments made regarding my client”.

A DUP spokesman confirmed that Mrs Foster and Mr Stalford and received the legal letters and would be “responding through their own legal representatives”.

It is understood that Mr Stalford, the DUP MLA for South Belfast, is facing the legal threat over comments which he made in an interview with RTE subsequent to the interviews which Mr Bell and Mrs Foster gave to the BBC and which were broadcast on 15 December.

Meanwhile, Mr Bell is understood to be on the list of MLAs who have asked to speak in Monday’s Assembly debate on emergency legislation to rein in RHI costs.