Mr Livingstone later offered an olive branch to Mr Johnson by closing an attack website aimed at the Mayor as he warned the election race was getting "out of hand". He said:
"Those of us who are leading candidates in this election have a duty to the electorate to rein it in and direct it to the issues at stake for Londoners.
"I suggest to Boris Johnson therefore that he and I work together to raise the tone and spirit of this election."
More top news
A survey showing the number of 14-17 years olds who have tried the products has raised questions about their appeal to young people.
Advertising agency chief executive for Europe Chris Hirst calls for all parties to concentrate on how we make money, rather than spend it.
A touching note from a passenger thanking a pilot for getting her home safely in the wake of the Germanwings tragedy has gone viral.