According to experts, victims of an earthquake have the highest chance of survival if they are found within 24 to 48 hours of the event.
Many international rescue teams and relief agencies are still days away from reaching the disaster area.
International Rescue Corps, a UK charity which provides international rescue support in disaster zones and is widely respected as one of the world's leading search and rescue teams, said time was running out.
"Our team of 55 experts were dispatched to Iran within hours of the earthquake, but even then it has taken a considerable amount of time for them to get into Bam", said Julie Ryan, spokesperson for the charity.
"I spoke to members of the team earlier this afternoon, when they were outside Bam, making their way to the effected area".
Specialist teams now have less than just a few hours to realistically find survivors amongst the devastation.
"Our teams have specialist equipment, including thermal heat seeking cameras which we put into the ground to try and
"We have special sound equipment that can detect the faintest of sounds and indicate a person who is shouting for help or moving in the rubble."
Those lucky to be alive wait to be
taken to hospitals across Iran
Older techniques are being employed too.
Swiss and Austrian rescuers with sniffer dogs were the first foreign teams to start hunting for trapped survivors. But they were finding the going tough.
Quoting colleagues on the ground, a spokeswoman for the Austria-based International Rescue Dog Organisation, Christiane Geritzer, said the canines' work in Bam was however "very difficult if not hopeless" because of the extensive damage to the largely two-storey buildings.
Roland Schlachter, heading the team of 10 Swiss rescuers from the Swiss Corps for Humanitarian Aid, said chances of surviving were extremely low.
"It has to do with the way the houses were built and have collapsed - there appears to be very few air spaces created when the buildings collapsed," he said.
Responsibility for coordinating rescue work in earthquake zones usually rests upon international agencies once the government of the affected country has given them the green light to fly in.
"With collapse of homes and buildings come the collapse of local government, emergency services and that's where
we come in and assist countries with our experience", said Ryan.
"The fact that the Iranians were so quick to seek outside assistance means that international teams have some chance of finding survivors."