Mr Holland, speaking from the 20-strong team's makeshift base on a football pitch in the heart of Bam, said the earthquake had virtually destroyed the historic city.
He said: "We have not found any survivors - but we have found quite a few bodies.
"In this type of situation the chances of finding someone alive are quite low, to be honest. As more time goes on, obviously the chances dramatically lower."
But he said it was too early to give up all hope and cited the discovery of an 11-year-old boy by a Rapid-UK search team amid the wreckage of the Gujarat earthquake in India after 84 hours.
The British Embassy in Tehran said that a Briton who was in the area is missing, while another UK national was slightly injured in the earthquake.
A further 28 Britons known to be in Bam, one of Iran's most important tourist sites, escaped the earthquake unhurt.
The UK Government has pledged £150,000 to help pay for emergency supplies.
Sniffer dogs
British rescuers flew from Stansted Airport in Essex to Kerman, 125 miles from the epicentre of Friday's quake, which also injured thousands of people and destroyed around 70% of homes.
Rapid-UK's team have been sifting through rubble from 18 buildings so far, including schools and hospitals.
They have specialist equipment with them, including snake-eye cameras, high-tech listening devices and carbon dioxide detectors, to search for people trapped under buildings.
Members of the International Rescue Corps (IRC), sniffer dogs, and fire and rescue teams from Essex, Hampshire and Kent also flew out to assist in the search operation.
Rescue specialist Paul Worcester said their dogs, which had been working "flat out", were getting tired.
He said the team would continue to work round the clock for the next 24 hours in the hope of getting someone out alive.
"People were bringing out their dead children, wrapped in sheets"
Earthquake survivor Ruth Millington
