Alice Gross missing: Police discover knife in London river in search for 14-year-old schoolgirl

Alice Gross disappeared in late August

Police are searching for Alice Gross, who went missing in August (Met Police)

Police searching for missing schoolgirl Alice Gross have discovered a knife in a west London river.

In Scotland Yard’s biggest search operation since the July 7 bombings, specialist teams searched the River Brent near Ealing Hospital and an industrial estate on Monday afternoon, in an attempt to find clues in the hunt for the 14-year-old.

At around 3pm, the force retrieved a six-inch knife from the water but the Metropolitan Police said it was too early to say if the blade was linked to the 14-year-old’s disappearance, the Mirror reported.

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.

The find comes after the Metropolitan Police were criticised for waiting four days to ask Latvian authorities for help in finding suspect Arnis Zalkalns, who served seven years in prison after he was convicted of murdering his wife Rudite Zalkalns in his native country in 1998.

Mr Zalkalns has been missing since 3 September – six days after Miss Gross was last seen on CCTV walking alongside the Grand Union Canal in west London, towards her home in Hanwell.

15 minutes later, Mr Zalkalns was seen riding past the same spot on a mountain bike.

A general labourer who works at a building site in Isleworth, west London, Mr Zalkalns, is thought to have come to the UK in 2007, but authorities here apparently had no record of his murder conviction.

Before he vanished, Mr Zalkalns left his passport at his house in Ealing, west London, and police in Latvia confirmed he has not entered the country by plane but conceded it was possible he could have got in undetected if he travelled by car or coach.

During the investigation, it also emerged that he was arrested on suspicion of indecently assaulting a 14-year-old girl in the UK in 2009, but the girl did not launch a case.

Scotland Yard have insisted they have no evidence to suggest that Alice, who suffers from anorexia, has come to harm.

A reward of up to £20,000 is being offered for anyone who has information that leads detectives to find Alice.

Mr Zalkalns is white, 5ft 10ins and stocky, 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 have asked anyone who sees him not to approach him and to dial 999.

Additional reporting by PA