UK officials' efforts to help British survivors of Hurricane Katrina have been defended by the prime minister.
British survivors have been arriving back in the UK
Some survivors have said the response was slow and information scarce.
Tony Blair said: "I'm really sorry if there has been difficulties...but I can assure you some of these staff have been working round the clock."
The British Consul General in Houston praised her staff's "enormous efforts", and said US officials had initially denied diplomats access to New Orleans.
Meanwhile, more survivors have arrived back in the UK and efforts continue to locate about 130 Britons still missing.
The Ministry of Defence has sent the first of 500,000 food ration packs to help the US aid effort.
'On the spot'
Defending British efforts, Mr Blair said: "I know if you are out there and have been worried about your own life you are naturally angry and wonder if more could be done."
He promised that officials would do all they could to get any Britons still stranded to safety.
British Consul General in Houston Judith Slater told Channel 4 News: "At the highest level of the Louisiana government, we were denied access."
Ms Slater said, once inside the city's Superdome, UK staff had helped other nationalities, as well as Britons.
"We have so far physically helped about 50 British refugees, most of whom are now on their way back to the UK.
"We have helped them in different ways, ranging from hugs and comfort and cups of tea through to logistics with their flights..."
After days trapped in New Orleans, a number of Britons said they had not been given adequate help from UK officials.
Jamie Trout from Sunderland said his group had contacted the British embassy in the US to ask for help, but was told to contact British officials in New Orleans instead - even though their office was 15ft under water.
Jane Wheeldon, 20, from Carmarthen, said: "They may have been trying to help us, but we never saw a single thing and even right until the end there was just minimum help that they gave."
Foreign Office minister Lord Triesman said he was "very disappointed" to hear of such complaints.
He said that although consular staff had done an "astonishing job" he would "insist that people must provide the service that British citizens are entitled to get".
The official response was further criticised by shadow home secretary David Davis, who said: "The Washington embassy is one of the biggest and best-equipped embassies we have in the world, and I would think that they could do a decent job if anybody could."
Figures of those missing were based on calls from worried relatives, and Lord Triesman said he expected the final number of UK casualties to be "very much smaller" than the 130 people currently unaccounted for.
A civil aircraft loaded with 500,000 standard issue MoD ration packs - boxes which contain enough food for one person for 24 hours - is on its way to the US.
Survivor Jane Wheeldon said UK officials gave "minimum" help
Brigadier Chris Steirn, who is overseeing the airlift, said 10 flights were scheduled between Monday and Friday, and more may be added.
Brig Steirn said: "We are looking at temporary accommodation and blankets and other facilities, but at the moment rations are the first request we have had to act on."
He said although the US was the world's richest country, it still needed help: "You don't have billions of these rations stacked up in one place and so they are quite often traded between nations."
Meanwhile, Sir Nicholas Young, chief executive of the British Red Cross, urged Britons to give money to help those affected by the disaster.
Relatives of Britons in the areas when Katrina struck can call a UK helpline: 0207 008 0000 or contact the British consulate in Houston on 001 713 659 6270.
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