Detectives searching for missing teenager Alice Gross have formally requested full details of the murder conviction against the prime suspect in her disappearance, Scotland Yard confirmed.

Police said an international letter of request has been sent to Latvia to obtain the full file on the case of Arnis Zalkalns, who served seven years in prison after he was convicted of bludgeoning and stabbing his wife Rudite Zalkalns to death in his native country.

The operation to find Alice, 14, has come under scrutiny after reports police did not immediately seek help from Latvian authorities in the hunt for the prime suspect. Officers searching for Zalkalns waited for four days before approaching officials in the country, according to The Times.

The Metropolitan Police were said to have made contact with their counterparts in Latvia over the weekend as the force carries out its biggest search operation since the 7/7 bombings, after Alice, 14, disappeared on August 28.

A Scotland Yard spokesman said: "We are maintaining a close and productive relationship with the Latvian authorities in relation to this investigation.

"We are not going to elaborate on the nature of information sharing with Latvian authorities."

The inquiry has focused on Zalkalns, 41, after he too went missing on September 3.

His passport was left at his house in Ealing, west London. 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.