The accident struck at the shrine of Imam Hamza, connected to the family of the Prophet Mohammed.

"Scaffolding being used for renovation work collapsed inside the mausoleum, killing six men aged between 20 and 35," an official of the pilgrimage site said, asking not to be named.

Medical and security sources confirmed the toll, with the latter adding that a woman and three-year-old child were injured.

A security source, also on condition of anonymity, said an investigation had been opened and that the accident was suspected to have been "the result of negligence on the part of people in charge of installing the renovation structures".

Corruption and lack of finances in both Iraq's private and public sectors often lead to the use of and poorly equipped and under-qualified maintenance crews in buildings and on infrastructure used by the general public, with safety procedures flouted.