A spokesman for Boris Johnson has said: "Boris Johnson has repeatedly made clear he pays all taxes in full. Ken Livingstone knows this because he has been personally told by Boris Johnson during a private conversation at a business hustings just two weeks ago.
“Mr Livingstone repeated these false claims today, knowing full well they are not true, in a desperate attempt to avoid answering serious questions over his own tax affairs".
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A High Court judge ruled he was entitled to "more than nominal" damages from police over a wrongful arrest he says destroyed his career.
The ex-Holby City star, who had been visiting Barcelona, detailed the events of the attack on Twitter as they unfolded.
Searches are continuing for victims, with around 600 people still missing and 3,000 left homeless after the disaster.