The hunt for missing schoolgirl Alice Gross has led to the biggest search operation since the 7/7 bombings, Scotland Yard said.
Police have been searching for the 14-year-old for 24 days after she went missing on August 28.
Convicted murderer Arnis Zalkalns, 41, has been named as the prime suspect in the disappearance after he too went missing on September 3.
The Metropolitan Police said that 600 officers from eight forces have searched nine square miles of open land and 3.4 miles of canals and rivers in the largest deployment of search assets for an ongoing investigation since the terrorist attacks of 2005.
Specialist search trained officers, police dogs and divers have been mobilised.
Investigators have received more than 630 calls and additional staff have been drafted in to man the phones.
Detective superintendent Carl Mehta, said: “Our thoughts continue to go out to Alice’s family as our search continues in a bid to find her.
“I would like to thank the local community who have shown great support to the search effort and police investigation so far.
“Our officers are working through the weekend – carrying on those searches. We will not stop our hunt for Alice.
“Whilst we have already seized many hundreds of hours of CCTV we still need the public’s help.
“If you are a shop owner, have CCTV at your home, or were out filming in the areas of Ealing and Hanwell and have footage from the afternoon of Thursday August 28 when Alice was last seen, and right up to September 3 when Arnis Zalkalns was last seen, then please get in touch with us.”
Police yesterday recovered a red Trek mountain bike belonging to Zalkalns but would not say where or in what circumstances.
Forensic teams yesterday scoured a property in Hanwell, west London, where his partner was thought to have previously lived.
It is the same area where 14-year-old Alice is from, and lamp posts less than 100 yards from the house feature posters appealing for information about the missing girl.
Onlookers at the house said they saw police remove a large parcel wrapped in brown forensics paper in the afternoon, with a police label that read “black mountain bike”.
Radoslav Andric, the landlord of the terraced rental property which is split into seven bedsits, said Zalkalns’s partner had lived there until about a year ago and that he stayed there with her.
Mr Andric, 64, who owns a flooring company, said he last saw Zalkalns there about two days before he went missing when he returned to see friends, bringing a broken blue bike to the house.
The landlord, who is originally from the former Yugoslavia and lives in an annexe at the rear of the building, said he believed Zalkalns had come back because his bike was not working properly.
Police had previously searched a semi-detached house nearby in Castlebar Road, Ealing, where Zalkalns has been living with his partner and their young child.
Alice has not been since she was spotted on CCTV footage walking alongside the Grand Union Canal in west London.
Zalkalns, who was convicted of murder in his home country in 1998, was seen 15 minutes later riding past the same spot on a mountain bike.
He has not accessed his bank account or used his mobile phone since he went missing. His passport was left at his house.
Scotland Yard have insisted they have no evidence to suggest that Alice, who suffers from anorexia, has come to harm.
Detectives have said that Zalkalns, who was convicted of bludgeoning and stabbing his wife Rudite Zalkalns to death in Latvia and served seven years in prison, was also arrested on suspicion of indecently assaulting a 14-year-old girl in 2009, but no further action was taken.
The general labourer, who works at a building site in Isleworth, west London, is thought to have come to the UK in 2007.
Police said on Thursday that it was their understanding there was no record in the UK of his murder conviction.
A reward of up to £20,000 is being offered for anyone who has information that leads detectives to find Alice.
Zalkalns is described as white, 5ft 10ins, of stocky build and with dark brown hair that he normally wears tied in a pony tail.
Police have said that he “potentially poses a risk to the public” and asked anyone who sees him not to approach him and dial 999.