Police have made a thirteenth arrest as part of the investigation into the abduction of three young boys by their father from a foster home in south London.
Detectives say Bilal Safi, Mohammed Ebrar Safi, and Mohammed Yaseen Safi - aged six, five and three - were taken from their home in Coulsdon a week ago.
According to their foster carer the youngsters were playing in the garden when their father Imran Safi, 26, threatened her with a knife. Officers said he took the children and they have not been seen since.
Police are working closely with national and international agencies in case the children have been taken abroad.
Safi is an Afghani national, and has links to Pakistan. At this stage, it is not known if he has travelled overseas.
A 31-year-old man has been arrested at a residential address in Ilford, the Metropolitan Police said on Saturday.
A police statement said: "Detectives investigating the abduction of three brothers have made a further arrest, taking the total number of arrests now to 13 over the past five days.
"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."
More than 100 officers are currently working on the case which has been described as "incredibly complex and fast-moving".
Commander Jon Savell, said: "Our absolute priority at this moment in time is the welfare of these three children. They have been taken from a place of safety and we are growing increasingly concerned about their wellbeing, particularly as we remain in the midst of a global health crisis."
Police also want to trace a red Nissan Qashqai, registration PK13 WFO, and hear from anyone with information about its movements on the afternoon of Thursday, 20 August in the Croydon area.