Kate McCann wept uncontrollably yesterday as she said she believed that her daughter, Madeleine, may still be held captive in an abductor’s home.

She revealed in her first television interview since she was made a suspect in Madeleine’s disappearance that the family had recruited private detectives to collect information about sightings.

McCann said, “I think she is possibly being held by someone in their house, but I don’t know. As Madeleine’s mummy I feel in my heart that she is there.

“I don’t know how anyone could harm anyone as beautiful as Madeleine. I don’t mean her appearance, I mean as a beautiful person.”

McCann and her husband, Gerry, have insisted that their daughter was abducted by a stranger from their holiday apartment in Praia da Luz in the Algarve on May 3.

During an interview on a Spanish television programme broadcast last night she broke down after saying: “I feel sad and I feel lonely and our life is not as happy without Madeleine. I feel anxious she is not with us.”

The McCanns gave the interview on the advice of private investigators, based in Spain, who have been hired by the couple. The investigators have set up a confidential 24-hour phone line to take calls on the case.

The McCanns had previously been warned that they could be prosecuted under Portuguese laws of judicial secrecy for speaking about the case.

However, their lawyers approved the interview on condition that they did not discuss evidence.

The couple spoke on the Spanish channel Antena 3 because they wanted to promote the helpline across the Iberian Peninsula and also North Africa. They are confident that the helpline does not break Portuguese laws banning outside involvement in criminal cases.

McCann, 39, said, “It is six months and I strongly believe Madeleine is out there and we have to do everything we can. Somebody knows something. It is not about us, it is about Madeleine. We have not even seen her since she was 4. She needs our help. She needs her family.”

McCann, who is a GP, said that her two-year-old twins, Sean and Amelie, still asked about when their elder sister would be returning to their home in Rothley, Leicestershire.

“They are not upset and they are not distressed but they are very much aware she is not there,” she said. “The hardest thing for me is when they say, ‘When is Madeleine coming back home?’ and we have to say, ‘We don’t know but everyone is looking for her’.”

Gerry McCann, a consultant cardiologist, said, “The thing is we want people to come forward with any information whatsoever that can help to find her and we want them to be aware of this number.”

The couple are suspected by Portuguese detectives of accidentally killing their daughter six days before of her fourth birthday and then illegally disposing of her body before inventing a claim that she had been abducted.

Three Portuguese detectives are expected to arrive in Britain this week to reinterview at least four of the seven British friends who were on holiday with the McCanns at the Ocean Club resort. The Portuguese detectives are expected to be present during interviews conducted by Leicestershire police officers.

Gerry McCann said, “We have not been charged with anything. Investigations are continuing. We are certainly not scared. There is no evidence DNA tests will show anything other than us being completely innocent.”

The information hotline is being operated by the Barcelona office of Método 3, one of Spain’s best-known firms of private investigators. Clarence Mitchell, spokesman for Mr and Mrs McCann, insisted that the new helpline would not side-step the Portuguese police investigation into her disappearance.

“This, in effect, is going to be a complementary structure,” he said. “One where our own investigators are able to chase things up very quickly, follow up any potential leads, and I would stress that any credible information that comes in to the phoneline is immediately shared with the respective police forces, either in Spain, Portugal or North Africa, depending on what the information is.

“This is not a sign of losing faith. We want this to be a collaborative exercise with the police.”