Harrowing hunt for the 71 Britons still missing amid the devastation of Hurricane Katrina

In the wake of the worst storm to strike America in living memory, the Red Cross is trying to reunite separated families

"You go to bed and think about your day and try and focus on the individuals that you have been able to help," said the tracing specialist, who also worked in Bam, Iran, after the earthquake and in the aftermath of the tsunami in Sri Lanka. "Then you think about the ones you haven't, and wonder if you spent enough time with them and made them feel any better."

She knows the horror British families are enduring. She has seen it on the faces of the displaced living in 133 shelters in the region. Yesterday the Foreign Office said 71 Britons are still missing. "The British can only be going through the same as those here," Ms Nazari said. "It's torture not knowing where people are and waiting to find out. Even if everything is being done I have no right to say to an individual that they have to be patient, because I know I wouldn't be."

Joseph Cordon, from the Isle of Wight, is one of them. He is desperate to hear from his sister, nephew and his nephew's family, all of whom live in New Orleans. The last time he spoke to his sister, Miriam Staiano, for their monthly "family chinwag" was just before the hurricane hit. Miriam, 81, a GI bride born in England, has been living alone in the Jefferson area of the city, near the breached levee, since her husband Vincent died last year.

That was also the last time Joseph spoke to her son, Michael, born in Britain, who lives five miles away in Metairie. Also missing are Michael's wife, Carol, their two children, Katherine and Patrick, and Carol's mother. Michael, who is about 60, is a manager at the city's Brooks Brothers clothing store.

"It's very worrying," said Joseph, 76, a retired fireman, who lives with his wife Ida, 72, in Bonchurch. "I phone them both twice at day, first at one and then between five or six just in case the sheriff or troopers are in the house. But the phones are just ringing. Miriam told me she was worried about the hurricane. It was the last thing we talked about. She was alarmed because the levee gets breached; it breached about 30 years ago. They knew the hurricane was imminent and she thought she would probably have to be evacuated.

"I don't mean this disrespectfully, but I'm not so worried about Michael because he's fit, he was a captain in the air force and he can organise his family. But Miriam is wheelchair-bound. Being an ex-fireman I know the difficulties they are up against out there. My wife and I pray for my sister, and the church is phoning regularly to see if we know anything but it's always the same. I'm a bit of realist. I think it's looking very bad for Miriam."

Every day, Joseph goes to the home of his son, David, while he checks the internet for news. They have added Miriam's details to the family links register on the American Red Cross website, set up after the hurricane. It lists more than 197,000 people, about 70 per cent of whom are missing. The rest are the names of those who have registered themselves as safe, details of their location and how they can be contacted.

Ms Nazari, part of a four-strong team of international Red Cross workers, has been visiting shelters, offering use of mobiles phones to those who need them. In areas where there is no network coverage or internet access, people are given forms to fill in which are sent to Washington, where the details are added to the family links register. So far, they have helped at least 12 people find family members.

One was a woman in her thirties who had lost all hope of finding her sister. "We found her sister's details and phone number on the website and went to the shelter with the mobile phone and told her we had managed to find her," Ms Nazari said.

"The woman kept saying it couldn't be her sister and she wouldn't know how to register on the website. I think she was scared; she was convinced she had died and didn't want to get her hopes up. We dialled the number and passed the phone. As her sister spoke, all of a sudden the expression on the woman's face changed. It was so instant. There were tears and she kept saying, 'Oh my God, oh my God. I can't believe you're alive.'"

Nearly 2,000 parents are still desperate for news of their children. Louisiana officials have custody of 50 children separated from their parents. The state is searching for their families and caring for the children at various sites.

"It's really difficult sitting with someone frantic to know what has happened to their children," Ms Nazari said. "They talk about the time before the hurricane, which school their child went to and their favourite toy. It's either the past or the future; they don't really want to discuss how they lost contact. They feel guilty they can't do more and ask themselves how is it that they are OK but they don't know where their child is.

"They want to talk to you about the family they have lost even though they know you are trying to trace living people. This is a human service and you sit with them having a coffee and they tell you their story. Some are heartbreaking. Sometimes I get upset and tearful.

"The culture here is a lot more tactile and it's OK to reach out and you'll have a hug and they know you can't say anything to make it better, but they feel relief telling you. Usually it's a silent hug."

When Ms Nazari returns to the UK, before the end of the month, her experience in Baton Rouge will stay with her for a long time, particularly at night. "I will feel relieved, selfishly relieved, because I will be home and safe and with my family and friends," she said.

"But always for a long time there is frustration. I wonder whether I should have gone there; maybe there was someone in the shelter that we missed out that we could have helped. It's hard to let go of what you've done."