There are few signs left of the killer earthquake that reduced to rubble the Iranian city of Bam and its celebrated citadel, but a decade later survivors are still haunted.

The 6.6 magnitude quake struck at dawn on December 26, 2003, devastating Bam, killing 26,000 people and leaving 75,000 homeless.

Nearly 80 percent of Bam's infrastructure was damaged, while the desert citadel, once considered the world's largest adobe building, crumbled.

The disaster was so severe that Iran agreed to open up its doors to international aid, even allowing US planes loaded with humanitarian supplies to land on its soil for the first time since the two countries severed relations in 1980.

Reconstruction experts rushed to rebuild Bam and UNESCO inscribed the citadel on its World Heritage List, marking it "in danger" following the quake.

A decade later the city has come back to life and the United Nations Educational, Scientific and Cultural Organisation has removed the citadel from its danger list.

Japanese engineers have repaired the water distribution system, while French experts helped to build a hospital.

A new quake-proof bazaar also emerged from the ruins of the old one in the historic district, and new steel-structured homes were built replacing the mud brick ones of yore.

A ceremony to mark the 10th anniversary of the quake is to be held Thursday at the Fajr (Dawn) sports complex which director Behzad Bahmanian calls "the symbol of our rebirth".

In his office, overlooking the 6,000-seat stadium, Governor Hossein Zainol Salehi said most of the reconstruction was completed four years after the quake struck.

"Bam is now the most quake-proof city in the country," he said, noting houses had been rebuilt with stronger construction material but that traditional architecture had been respected.

'Cracks with every jolt'

Salehi said the reconstruction drive cost nearly 20,000 billion rials, or about $667 million at the current exchange rate -- an astronomical amount in sanctions-hit Iran.

"But this is not enough to solve all the problems," he said, noting many residents were still in need of psychological support for trauma suffered from the quake.

Although Bam residents say they are grateful to "all the foreigners who helped" them rebuild their lives, some doubt the new infrastructure is truly quake-proof.

"We see new cracks with every jolt," said Yasser, a DVD merchant in the bazaar which was flattened in 2003 but completely rebuilt after four years.

Iran sits on seismic fault lines and has been hit by many earthquakes of various magnitudes over the years.

Yasser, 26, said he is still traumatised by memories of the 2003 quake and recalled that not so long ago he fled his home and pitched a tent in the street after Ban was hit by a minor temblor.

"It is always the same, we are always afraid, even after a little quake," said Ali Moshki, who lost six family members in the disaster.

Governor Salehi said the reconstruction was essential for Bam's economic revival and its 107,000-strong population -- 17,000 more than a decade ago.

Traditionally known for its dates and oranges, Bam has also been bolstered with a vast industrial zone on the outskirts of town which is churning out 100,000 Chinese cars annually.

"We welcome all investors with open arms," said Salehi.

The city received almost one million visitors before the 2003 quake, and is hoping to revive its tourism industry, he said, adding there were 150 sites to visit in addition to the citadel but not enough guest rooms.

Salehi said he was hoped to build more hotels in Bam, where there are only two four-star ones and some motels.