“Our enquiries are moving at pace and I urge anyone who saw anything suspicious at the locations concerned to contact us.”
The Bomber Command memorial was erected to honour the sacrifice of the 55,000 members of aircrew from Britain, Canada, Czechoslovakia, Poland and other countries of the Commonwealth as well as civilians of all nations killed in raids.
It was unveiled by the Queen in 2012 after a public appeal for funds raised more than £5 million.
The RAF Benevolent Fund said it was the fourth time in six years that the Bomber Command Memorial had been vandalised.
It was first targeted in 2013 when a man daubed the word “Islam” on it shortly after the killing of Fusilier Lee Rigby outside Woolwich Barracks.
A week later, a second man wrote “Lee Rigby’s killers should hang”, “EDL” and “F*** the police” on the memorial. He was jailed for 12 weeks.
Britain’s last surviving Dambuster George “Johnny” Johnson, 97, slammed the latest incident.
He said: “What a disgrace, such mindless vandalism.
“How disrespectful to the nearly 58,000 people who gave their lives so that these thugs have the freedom to carry out such acts? I hope they are caught soon, and suitably punished.”