Lawyers for Lord McAlpine are expected to take a tougher line over "principle tweeters" who mentioned false child abuse allegations about the Conservative peer on the social networking site, The Sunday Times (£) reported.
QI regular Alan Davies, a reporter for TV station Al Jazeera, a Guardian journalist, the Managing Director of a public relations company and a former barrister are among thousands of Twitter users who alluded to the allegations, according to the newspaper.
Lord McAlpine's lawyers have found 1,000 "original" tweets and an additional 9,000 "retweets" - in which an original message is forwarded on by another Twitter users - and said the case could involve the largest number of defendants in British legal history.
Mr Davies declined to comment on the story, the newspaper added.
Lord McAlpine will receive a payment of £185,000 after a settlement was reached with the BBC over false claims made in a Newsnight report.
George Entwistle will receive a 12-month salary after stepping down from the BBC, he is also reported to be entitled to his full pension.
BBC director general George Entwistle has fallen on his sword following the Newsnight child abuse scandal.