A part of the main entrance of the 18th century Pucca Qila in Hyderabad collapsed on Thursday afternoon.

There were no reports of casualties or injuries. Witnesses and residents gave conflicting versions with some saying work was being carried out while others said there was no one at the site when the entrance collapsed around 1pm.

Conservation work on the Qila's fortification wall was being carried out for some time by the Sindh culture department's Planning and Development Monitoring Implementation Cell (PDMIC). Some of the work on the part of the wall facing Bacha Khan Chowk had been completed by the department.

Sindh Culture Minister Syed Sardar Ali Shah said the department would be conducting an inquiry into the collapse. However, a conservation plan would have to be made before the work could be resumed, he added.

Shah said the culture department had carried out conservation work on some parts of the wall as it was in a dilapidated condition.

The work was difficult because shops had been set up along the Qila's wall, he said. "A big population lives inside the fort as well. So, it is quite a tricky job," he said.

Manzoor Kanasaro, director general of the culture department, also said that an inquiry had been ordered to find out the reason behind the collapse.

He said that nobody had expected the structure would cave in during work, adding that mud was now being removed from the site by labourers.

"Luckily, no one was passing through the area when the structure fell," a resident whose shop is located outside the entrance told Dawn.com. He said that a government school was located inside the fort. "It is usually the school's ending time and students start leaving the premises. But nobody passed through at that time. Even the labourers were away from the site," he added.

The fort was built by Ghulam Shah Kalhoro, a former ruler of Sindh, in 1768 before the Kalhoros were overthrown by the Talpurs in 1783 in the battle of Halani. The Talpurs were later defeated by Charles Napier's forces in 1843 in the battle of Miani.

The fort has been in a dilapidated condition and awaiting conservation work for a long time. The culture department has not been able to complete the work as it requires shifting a large population. Every monsoon, rains tend to damage the wall at various locations.

A survey conducted some 16 years back found many houses and structures inside the fort were dangerous and advised the inhabitants to vacate them but they declined to move to any other place.