Madeleine's parents prepare to return to UK for the sake of their twins

Despite having vowed to remain in Portugal until Madeleine is found, the McCanns are now coming to terms with the reality that they cannot stay abroad with their two-year-old twins indefinitely.

Kate and Gerry McCann have told friends that, for the sake of twins Sean and Amelie, they will return home soon and are close to setting an exact date.

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A friend said: "They have to make sure the twins are protected and do everything they can to look after them. That means a stable home life and routine - and they can only do that in the UK.

"At home there is a strong support network with lots of friends and family around to help. They know their home is in Leicestershire and they have happy memories of that home.

"They are getting close to setting a date for coming home."

The couple are renting in a villa while the search carries on but the lease is paid only until the middle of September.

And campaign manager Justine McGuinness, who has overseen their media relations for two months, is leaving her post at the same time.

During the 108 days since four-year-old Madeleine disappeared, the McCanns have been paying their living expenses out of their savings, as well as the mortgage and bills on their home in Rothley, Leicestershire. The villa alone is costing them £1,200 a month.

Mrs McCann, 38, has left Portugal for only two days at most since Madeleine was abducted and has not been able to work as a GP. Mr McCann, 39, has been on unpaid leave from his post as a cardiac consultant at a hospital in Leicester.

Some of their expenses in Portugal have come from the £1million Find Madeleine Fund but they are reluctant to use this for day-to-day living.

The most pressing reason for them to return home is the welfare of the twins, who have mostly remained at their parents' side in Portugal.

The McCanns have tried to maintain a stable routine for Madeleine's brother and sister, taking them to a daily creche and playing with them in the afternoon. But now they have decided they need to return to normality in the UK.

On Friday, they told the twins for the first time that Madeleine is missing and "Mummy and Daddy are looking for her' after receiving advice from a British child psychologist on how best to break the news.

Previously they have said their sister was 'on a little holiday' and would be back soon.

In a further sign that they are laying the ground for a return home, Mrs McCann told local newspapers she had discussed leaving Portugal with her husband.

She said: "We know we will be going back and I guess one day we will wake up and it will be right. We never thought we would go before Madeleine came back. Now we just don't know but we have our twins to consider."

Mr McCann has previously acknowledged that staying in Portugal might not be the best thing to do but his wife feels a strong attachment to Madeleine in Praia da Luz and has been reluctant to leave.

Portuguese press reports based on unnamed police sources yesterday claimed a breakthrough in the investigation could come this week. The police would not verify these reports, however, and they have proved unreliable in the past.

The daily paper Correio Da Manha claimed possible DNA traces of Madeleine had been found in one of the vehicles hired by friends of the McCanns and that detectives have a 'concrete' British suspect.

The report also claimed witnesses, including the McCanns' friends, are to be reinterviewed and further searches carried out this week, when the full results from the UK Forensic Science Service are expected.

The lab is also testing specks of blood found on the wall of the McCanns' apartment. Although it was claimed last week that preliminary results show it came from a Northern European man, police have refused to confirm or deny this.

Meanwhile, police in Belgium confirmed that a girl suspected of being Madeleine seen at a roadside cafe in the country was actually the four-year-old daughter of a local man.