Bernard Hill and Victoria Hamilton play Mr Blunkett and Ms Quinn

Mr Blunkett is understood to have also telephoned chief executive Andy Duncan about the drama exploring the affair with publisher Kimberly Quinn.

A Very Social Secretary was announced in More4's schedules at the Edinburgh International Television Festival.

Current London play Who's the Daddy? explores Mr Blunkett's private life.

A forthcoming musical will also look at the work and pensions secretary's relationship with Mrs Quinn.

A Channel 4 spokesman on Friday said: "I can confirm that we have had correspondence from solicitors acting on David Blunkett's behalf."

It is believed Mr Blunkett is seeking to protect the interests of Mrs Quinn's boy William, who he claims is his son.

Channel 4 is standing by the programme.

Stuart McQuarrie plays Boris Johnson, editor of The Spectator

Other More4 programmes will include a dramatised documentary on animal experimentation, a documentary series by Super Size Me director Morgan Spurlock and a late-night discussion programme, The Last Word.

The latter will feature columnist Stanley Johnson as a regular guest. His son, Spectator editor Boris Johnson, is played in A Very Social Secretary by actor Stuart McQuarrie, with Robert Lindsay as Tony Blair.

Mr Blunkett is now the Work and Pensions Secretary.

More4, which has a �33m programme budget, is a companion service to Channel 4's existing digital network E4.

It is targeting over-35s with a schedule dominated by factual programming, drama and movies.

The latter include the UK TV premiere of Downfall, the Oscar-nominated German film about Hitler's last days, and Irish drama The Magdalene Sisters.

US imports include sitcom Curb Your Enthusiasm - previously seen on BBC Four - and the sixth series of White House drama The West Wing.

"We're excited about our launch line-up and convinced More4 represents a significant extension of choice for our viewers," said Andy Duncan, Channel 4's chief executive.