The Foreign Office is continuing to search the hurricane-hit region in the US for 96 Britons who remain missing.
British survivors have been arriving back in the UK
"Officials on the ground are still checking, trying to locate people. They are checking addresses and the last known whereabouts," a spokesman said.
He said most of the missing were people living long-term in the US.
One anxious relative is Tom Noone, 48, of Oxfordshire, who was "still waiting, still hopeful" for news of his brother Mike, 51, who lives near New Orleans.
Foreign Secretary Jack Straw has said many of the 96 missing could be safe and well but unable to get in touch.
The Foreign Office spokesman on Wednesday said: "We are still in contact with the families as well, just trying to see whether they have heard from the person they reported missing.
"Normally people are just so happy that they have managed to find a loved one they obviously don't think to call us."
Tom Noone's brother Mike lives north of New Orleans on the edge of Lake Pontchartrain.
The lake was reportedly hit by a 20ft-high sea surge when the hurricane struck.
"He is still missing and at the moment I am just waiting," said Tom on Wednesday.
"I am still waiting, still hopeful - people are being found all the time."
Jill Amend, from Richmond, Surrey, who has not heard from her son since the disaster, on Tuesday said she was feeling "very negative as each day goes by".
Ms Amend said she last heard from Vernon Carroll, 47, a few days before the hurricane struck, when he told her he would be in touch when he and his wife had reached a safe place.
"It is hard to describe - it is just an appalling situation. He is my only child, my only relative in the world," Ms Amend said.
No casualties confirmed
The Foreign Office spokesman also defended officials' early response to the hurricane.
"We have had a lot of praise from people who we have managed to find. Officials have been trudging through the sludge trying to locate people.
"The problem is that the people in the [Louisiana] Superdome had a really hard time and were not happy about our officials not being allowed in there."
On Tuesday Foreign Office minister Lord Triesman said it was "always possible" that British citizens would turn up among the dead, but there had so far been no suggestions that there were any British casualties.
"Among the people we are still trying to track, many of them will turn out not to be in the area at all."
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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