A 31-year-old man has been arrested in east London in connection with the abduction of three young children by their father.
Metropolitan Police said the total number of arrests related to the case over the past five days now stands at 13, as officers hunt for Imran Safi, 26, and his sons.
Safi is believed to have snatched the youngsters, Bilal, six, Mohammed Ebrar, five, and Mohammed Yaseen, three, from their foster carer at knifepoint last Thursday in Coulsdon.
Neither the children nor their father have been seen since the incident.
Four men aged between 21 and 41, who were arrested on Friday morning on suspicion of being involved in the abduction have been released on bail.
They are believed to be known to the suspect and were all arrested at a property in Ilford, south East London.
In a statement the Met said: “Officers arrested the 31-year-old man at a residential address in Ilford on Saturday, August 29, on suspicion of conspiracy to abduct a child.
“He currently remains in custody at a south London police station.
“The four men previously arrested on Friday, August 28 at an address in Ilford – aged between 21 and 41 – were subsequently released and are due to return on bail to a south London police station on a date in early September.”
Eight other people – relatives and friends of Safi – have also been arrested on suspicion of involvement in the abduction and were bailed to a later date.
It is understood that the boys were shortly due to be formally adopted by a new family, which detectives believe could be a motive for the abduction.
The brothers were taken from the garden of an address in Croydon on the evening of August 20 while their carer was inside.
The carer said that Safi had threatened her with a knife before forcibly taking the boys and driving off with them.
It is not yet known if Safi, an Afghan national with links to Pakistan, has gone overseas, but detectives are working with national and international agencies to identify any travel.
An all-ports alert was issued shortly after they were taken and more than 30 calls have been received from the public since Thursday afternoon.
Scotland Yard is also appealing for information on the movements of a red Nissan Qashqai car, registration PK13 WFO, throughout last Thursday afternoon in the Croydon area.
Anyone who may have information regarding the vehicle, or believes they have seen Safi and the three boys since August 20, is asked to contact detectives immediately on 07942 599374.