Lord McAlpine's lawyer has warned that legal action was being prepared against ITV's This Morning and a lengthy list of Twitter users who identified the peer's name in connection with false sex abuse claims - and that it would cost them "a lot of money".

The warning came as the former Conservative Party treasurer neared a settlement with the BBC over false claims made in a Newsnight report, which led to the resignation of BBC director-general George Entwistle.

Lord McAlpine said the damage "can't be repaired", and that he has to live with the legacy of suspicion.

He said that his legal team would ensure that anyone who brought the matter up again would be "very, very foolish".

In an interview for Radio 4's World At One, Lord McAlpine said the BBC could have saved "a lot of agonising and money" by simply calling him before the programme went out.

Ofcom said that it was investigating the broadcast, which has further fuelled the crisis which has gripped the corporation since the Jimmy Savile scandal broke.

The regulator is also investigating ITV1's This Morning after presenter Phillip Schofield brandished a list of names of alleged abusers which he had found on the internet and handed it to the Prime Minister during a live interview, asking if he would investigate them. The stunt provoked fury last week, and ITV said that disciplinary action had been taken.

Lord McAlpine was mistakenly implicated by Newsnight's November 2 broadcast in a paedophile ring that targeted children at a care home in Wrexham in North Wales.

Although the programme did not name the peer - referring only to a senior Conservative from the Thatcher era - he was quickly identified online.

Lord McAlpine's solicitor, Andrew Reid, told the World At One programme that action would be taken against "a lot of people" who linked the peer's name with the unfounded allegations. And he called Schofield's actions "very low".