Palestinians rest at the rubble of a house destroyed by Israeli strikes in the northern Gaza Strip. Reuters

And unexploded ordnance buried in the rubble would complicate that work, said UNMAS' Pehr Lodhammar, who has run mine programmes in countries such as Iraq.

It was impossible to say how much of the ammunition fired in Gaza remained live, said Lodhammar. "We know that typically there is a failure rate of at least 10% of land service ammunition," he told journalists in Geneva.

"What we do know is that we estimated 37 million tonnes of debris, which is approximately 300 kilos of debris per square metre," he added.

Starting from a hypothetical number of 100 trucks, that would take 14 years to clear away, he said. Lodhammar was speaking as UNMAS launched its 2023 annual report on Friday.

Agence France-Presse