Kate and Gerry McCann are to be questioned by social workers about the welfare of their twins, Sean and Amelie, at a face-to-face meeting later this week, The Times has learnt.

The request from Leicester Social Services comes as the Portuguese prosecutor begins to review the case files against the McCanns, raising the prospect that he will order their return to the Algarve to face charges of killing their daughter.

Social workers and police in Leicester held a meeting yesterday to be briefed on the allegations against Mr and Mrs McCann and to discuss the children’s future.

Child protection experts will now meet the couple to assess whether the twins are at risk. Child welfare experts told The Times that involvement by social services was inevitable and did not mean that the children would be taken into care.

If the alleged offence had taken place in Britain, police would share all evidence with social services to help them to make a decision on whether other children were at risk. In this case, it is uncertain how much evidence has been shared with Leicestershire police by the authorities in Portugal that could be passed on to the social workers. The meeting with social services is part of an initial assessment on whether the children are at risk. If it is decided that they are not, the matter will not go any further.

However, a decision could be taken that a further detailed assessment, known as a “core assessment”, needs to be made. If that goes ahead other agencies such as the GP, the local hospital and police, would be involved. All this is standard procedure.

If there was any suspicion of imminent danger, social workers could move very quickly to remove a child from its home or require a parent to leave the family home. Social workers in this case have decided there is no immediate threat.

Experts said that even if there were to be a core assessment that the children were in danger, it was unlikely that they would be taken into care because family members were in a position to care for them.

John Coughlan, the joint president of the Association of Directors of Children’s Services, said last night that the interests of the children would be paramount. “Any individual case concerning the welfare of a child is judged on merits and based on evidence. The focus is always on the welfare of the child and also upon, wherever possible, helping a child remain with their own family,” he said.

A British couple who were dining with the McCanns when Madeleine disappeared are to be questioned again by police in Portugal, it was claimed yesterday. Russell O’Brien and Jane Tanner are expected to be asked voluntarily to return to the Algarve. They were among a group of five British adults and their children who had travelled to Praia da Luz with the McCanns. The couple will be questioned about new scientific evidence and in the light of statements given by the McCanns to police last week.

Dr O’Brien released a statement last month attacking “completely untrue” reports about him after Portuguese newspapers reported that police were about to arrest a man in Exeter, where he lives. The couple, both 36, were key witnesses in the early stages of the police investigation.

Ms Tanner reported seeing a man carrying a child away from the McCanns’ apartment – leading to police becoming convinced that she was abducted. Mr O’Brien claimed to have seen Robert Murat, the previous suspect, at the Ocean Club resort on the night Madeleine disappeared.

They had voluntarily returned to the Algarve in July to help the police investigation. Ms Tanner is reported to have arrived at the restaurant at about 9.20pm, shortly before Dr O’Brien left the table to look after his own daughter, who was unwell. Mrs McCann reported Madeleine missing at 10pm.

Dr O’Brien is alleged to have claimed that he saw Mr Murat, 33, at the Ocean Club at 1am. Mr Murat insisted that he had spent the night with his mother in their villa.

Both men are believed to have been in Exeter shortly before Madeleine was abducted.

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