This article is more than 6 years old

This article is more than 6 years old

The memorial commemorating the victims of the 7 July bombings in London has been defaced just hours before survivors and bereaved families gather to commemorate the ninth anniversary of the attacks.

The stainless steel columns of the memorial in Hyde Park were daubed with red and black slogans overnight saying "4Innocent Muslims", "Blair Lied Thousands Died" and "J7 Truth".

David Cameron "unreservedly" condemned the attack on the memorial, Downing Street said. The prime minister sent a floral tribute to be laid at it to mark the anniversary.

A spokeswoman for the Royal Parks said the slogans had been removed after their discovery early on Monday morning by the park's manager.

"We found it this morning," she said. "It has now been removed and the memorial can go ahead as planned. Obviously, we are very disappointed."

Video footage and photos tweeted by the London Live broadcast journalist James Banks shows the full extent of the defacement.

John Falding, whose partner Anat Rosenberg, a 39-year-old charity worker, was killed in the Tavistock Square bus bomb, condemned the vandalism.

"It is quite shocking. Whoever did it was aiming for publicity and to cause maximum grief."

Hyde Park staff clean graffiti off the 7/7 memorial. Photograph: James Banks/London Live/PA

He said he would not be attending the memorial but would be observing the anniversary in "quiet", lighting candles in memory of Rosenberg.

Scotland Yard said in a statement that police had launched an investigation into the vandalism. "Officers were called by a member of the public shortly before 3.30 this morning and informed of the graffiti, which is being treated as criminal damage. The graffiti consisted of several short sentences written in red and black paint and has now been cleaned off the memorial. Inquiries continue led by officers from Westminster – there have been no arrests at this time."

Police urged anyone with information that could help the investigation to call 101.

The monument honouring the 52 who died in the attack on London's transport system in 2005 cost nearly £1m and is made up of 52 stainless steel columns, or stelae, 3.5 metres (11.5ft) tall. It was unveiled on 7 July 2009 at a memorial attended by the Prince of Wales, the then prime minister, Gordon Brown, and other political leaders.

The columns are grouped together in four clusters, reflecting the separate locations of the bombings – Tavistock Square, Edgware Road, King's Cross and Aldgate. Four suicide bombers detonated their rucksack devices near these locations on the morning of 7 July 2005, killing the 52 and injuring hundreds of others, some seriously.

Graffiti was scrawled on the memorial two weeks after its dedication ceremony in 2009.

The mayor of London, Boris Johnson, said on Monday: "I am shocked and saddened by this incident. It is completely unacceptable and the Metropolitan police is already investigating. I am pleased that the graffiti has been removed so quickly and that today's commemoration ceremony can go ahead as planned.

"The focus today should be, and indeed will be, on honouring the 52 innocent people who died on 7/7, the survivors and all those affected by the terrible events of nine years ago."