The East Qin Mausoleum in Northwest China's Shaanxi Province has been under tight security ever since looters raided the ancient tomb.

The local cultural relics protection department and the police have assigned personnel to the East Qin Mausoleum and inspections are conducted on a daily basis, the Shaanxi-based Chinese Business View (CBV) reported Thursday.

The East Qin Mausoleum, which is next to the Mausoleum of China's first emperor Qin Shi Huang (259 BC-210 BC), was raided in October. Qin Shi Huang's parents and grandparents were laid to rest there.

The official confirmation has not been made that the tombs belong to the Qin family since no major excavation was conducted.

Archaeologists and historians, however, believe the mausoleum contains large amounts of treasures.

In early October, the looters blasted open a 36-meter-long path that leads to the main vault of the tomb and took away a historical relic, police said.

The police later arrested the looters and retrieved the stolen unidentified item.

It was not known if the looters made it to the main vault of the tomb. Police said that the looters hesitated whether they should go deeper into the tomb because they feared not having enough oxygen. But their boss pushed them to do so.

The 2,400-hectare East Qin Mausoleum was discovered in 1986 and labeled a national cultural heritage under special protection.

The looters told police they noticed evidence that other people had previously entered the area.

In fact, the tombs in the area have been raided repeatedly in recent years, the local Sanqin Metropolis Daily reported.