UPDATE: The 51-year-old arrested on suspicion of murder on 8 September has been released without charge
A second man is being questioned over the murder of missing schoolgirl Alice Gross.
The 51-year-old man was arrested yesterday afternoon in the schoolgirl's home area of Hanwell, west London, on suspicion of her murder.
Police have stressed that the man has no connection to another man was arrested on Saturday, who is 25.
Despite the arrests, police are stressing the disappearance of the 14-year-old remains a missing persons inquiry.
The development comes as officers expanded the area they are searching in their hunt for clues as to what happened to Alice.
The 25-year-old man arrested on Saturday is being questioned about the same offence, but officers have stressed the two men are "independent" of each other.
The pair remain in custody at a west London police station, Scotland Yard said.
Alice, who suffers from anorexia, went missing 12 days ago after she left her home in Hanwell in the afternoon, but failed to return.
She was last seen by her family at 1pm on August 28, and was captured on CCTV at 4.23pm that day walking along the Grand Union Canal near her home in Hanwell.
Specialist police divers in black wetsuits and breathing apparatus have been combing the west London waterway where she was last spotted.
Sniffer dog handlers with a golden Labrador have taken to the canal on a red dinghy boat to scan it for evidence.
Police swooped on the man in Ealing, west London, on Saturday afternoon after receiving new information following a fresh witness appeal.
It came after they released new pictures of five cyclists spotted riding along the canal around the time Alice went missing.
The grainy images show three cyclists passing by the Trumpers Way Canal Bridge in Hanwell, just before Alice walks past at 4.23pm.
They are followed by two more cyclists who pass under the bridge.
Police have trawled through hundreds of hours of CCTV footage and carried out "extensive" searches using specialist officers in the hunt for the missing schoolgirl.
Alice is white, 5ft 2ins tall, of very slim build and with shoulder-length, light brown hair.
She was last seen wearing dark blue jeans and a dark green lacy cardigan and carrying a dark rucksack, which was recovered earlier this week. She may have been wearing denim blue Vans shoes and tartan-framed spectacles.
Police said they were "especially concerned" as Alice has not been well recently.
Officers are also urging anyone who may have befriended Alice while on a song-writing workshop at the Camden Roundhouse to come forward.
Last week Alice's mother, Rosalind Hodgkiss, issued an emotional appeal to help find her daughter.
She said: "We'd like to say to Alice first of all that we miss her, that we love her and that she's not in any trouble, and we want to know that she's safe. We just want her to come home.
"We're also appealing to anybody who might have seen her or who may have made contact with her or who may know something about her whereabouts to contact police or Missing People, and to just get in touch because we're really concerned about her well-being."
Surrey and Sussex Police have both provided specialist resources to the Met to help with their search.
Anyone with information can call police on 020 8358 0100, Ealing Missing Persons Unit on 020 8246 1018 or the charity Missing People on 116000.