The many churches in the area around missing teenager Alice Gross' home have joined together to pray that she will be found.

The 14-year-old has been missing since the afternoon of August 28, when she was filmed on CCTV walking along the Grand Union Canal in Ealing, west London.

Police have been unable to trace Latvian convicted murderer Arnis Zalkalns, who is the prime suspect in the case. He was seen cycling past the spot where Alice was last seen 15 minutes after her, and has not been seen since September 3.

"We have been praying with each other ever since she went missing and praying every week in our churches," said Rev Suva Catford, minister of Hanwell Methodist Church.

"With the police camped on our doorstep you can't help but be concerned for all those involved in the investigation," she added.

Bless Community Church in Hanwell helped to organise a prayer tent for Alice at the Brentford festival on September 7.

Members of many churches have joined with the rest of the community in putting up posters and the 'find Alice Gross' yellow ribbons that now cover the area.

Alice's father Jose Gross, 60, said in an interview with the BBC yesterday: "The scale which people have been taking part... supporting us, sending us messages, as far as I can see is totally unprecedented, and it makes a really massive difference to us."

Her mother, Rosalind Hodgkiss, 50, said: "The longer Alice has been missing, the more worried and concerned that we feel, and obviously the greater the anguish that we feel.

"We're asking... people to come forward as witnesses if they have any information whatsoever about what might have happened to her or about where she might be now."

The investigation into Alice's disappearance is the largest police operation since the London terrorist attacks in July 2007. Hundreds of officers have covered miles of land and waterways around her home.

Today police have been scouring Elthorne Park, close to where she was last seen walking. Yesterday they filmed a reconstruction of the route that she is known to have taken on the day she disappeared.

A reward of up to £20,000 has been offered to anyone who has information that leads detectives to find her.

In an appeal to anyone who might be with Alice, her mother said: "Alice is desperately missed in our family. Every day without her causes us new heartache, new anguish. She needs to be at home amongst her family and friends who love her."