Shuttle scientist among the British missing

Mike Noone, 51, and two of his children have not been seen since a storm surge sent a two-metre wall of water through their home on Lake Pontchartrain, opposite the devastation of New Orleans.

The hunt for British survivors was stepped up after criticism of efforts made by consular officials prompted Tony Blair to apologise to those stranded in the aftermath of the disaster, while insisting diplomats had done everything possible to help.

The Prime Minister denied that UK citizens had been abandoned, despite the fact that the first two British officials entered New Orleans only in the early hours of yesterday, a week after the disaster.

Speaking at the start of EU-China trade talks in Beijing, Mr Blair said: "It's been really tough for people, I know that, but it's been tough for our officials on the ground ... I'm really sorry if there have been difficulties about this, but I can assure you some of these staff have been working around the clock."

The Foreign Office said more than 150 Britons had been evacuated without injury. But officials added that it was likely that some of those on the list of 131 missing will have died.

Mr Noone, an Oxfordshire-born scientist, who worked on the fuel tanks of Nasa's space shuttle, had recently moved with his teenage daughter, Marion, into a harbour-style development half a mile from the shore of Lake Pontchartrain, whose levee burst to flood New Orleans. Efforts to contact his youngest son, Ryan, and his American ex-wife, who also live on the north shore of the lake, have also failed.

Mr Noone's brother, Tom, 48, from Abingdon, Oxfordshire, told The Independent that satellite pictures on the internet showed that the engineer's home had been badly damaged. Tom Noone, a molecular scientist, said: "The pictures show the area where Mike lived. You can even zoom down to his house itself. It looks fairly wrecked. But even though I can look through his roof on the internet, I can't find out where he is. It's very frustrating. The communications are in chaos. There are no phone lines or mobile networks. You don't want to contemplate the worst, but it is always at the back of your mind. I just hope he and his family are sheltering in a hotel somewhere."

Other relatives of those missing described their desperation as they scoured news channels. Eddie Kittle, from Plymouth, Devon, whose son Ryan, 24, was in the path of the hurricane when it passed through Gulfport in Mississippi, said he had been contacted by consular officials only in the past 24 hours - a week after the storm.

He said: "We haven't got a clue what's going on over there. We've just heard from a member of the British consulate in Mississippi who said they had people looking for Ryan, but we've not heard anything since.

"We keep watching all the news programmes we can, to see if we can see Ryan in the background when they go to Gulfport and things like that. It's just grasping at straws really."

Ryan, a plumber who had been working on a floating casino wrecked by the storm, had called his family shortly before the hurricane arrived to say he would be staying in his home with his new wife, Inger. He was planning to go to Gulfport for wood to board up his windows.

Mr Kittle said: "The last thing Ryan said was: 'Don't worry Dad, it's not going to hit us.' That was a week ago, the day before the hurricane struck."

Also named as missing was Mike Healy, 48, a casino worker originally from Alcester, Warwickshire, who lived in Bay St Louis. His sister, Susan Betteridge, 52, said: "It's totally out of character for him not to contact us to say he's safe."

The list also included Dawn Holland, 54, from Islington, north London, who is married to an American airman and lives in Biloxi, Mississippi; Vernon Carroll, 47, from Richmond, west London, who lives in New Orleans; and Les and Kirsty Watson, from Doncaster, who were visiting relatives in New Orleans.

Some 30 consular staff are now manning a co-ordination centre in Houston, Texas. The American Red Cross has also set up a helpline for families to trace relatives.

The Foreign Office denied reports that some stranded holidaymakers had been told by the British embassy in Washington to contact the consulate in New Orleans, despite it being 20ft under water.