New York Mayor Mr Rudolph Giuliani said today some victims' remains may never be recovered from the attack on the twin towers of the World Trade Center.
"That's a very strong possibility," he said on NBC's
Today
programme. "Given the nature of this implosion and the temperatures - 1,000, 2,000 degrees Fahrenheit - we will not be able to recover every single person".
But he said rescue workers have not given up the search for life in the smouldering ruins of the twin 110-story towers, which collapsed after hijackers crashed two airliners into them last Tuesday.
No one has been pulled out alive from the twisted steel and concrete in lower Manhattan since the day after the September 11th attacks. A total of 5,422 people are missing and 233 confirmed dead from the trade center collapse.
Mr Giuliani said family members should understand that emergency workers would continue their rescue and recovery effort.
"We're going to try to find anybody that's alive. We're going to try find all human remains," he said. The mayor predicted workers would insist on continuing the search even if he or other authorities considered calling them off.
But Mr Giuliani said: "I am told by all the experts, including the military people, police and fire, that there are situations in which people have survived longer than the period of time we are talking about".
"In a separate interview with ABC's Good Morning America, he said the cleanup operation would take at least six months.