An exhibition of China's famous terracotta warriors at the British Museum is proving so popular that curators are planning the unprecedented step of opening 24 hours to cope with demand, a UK paper has reported.

The terracotta warriors sit on display at the British Museum in this Xinhua file photo taken on September 12, 2007 [Xinhua]

The museum anticipated the exhibit, the first time the ancient treasures have been displayed en masse outside China, would attract about 400,000 visitors when it opened in September.

But now, more than twice that figure is expected to see the afterlife tribute to Qin Shihuang, who became ruler of Qin State at the tender age of 13 in 246 BC before subduing warring neighbors and uniting China.

"We were confident that the exhibition would excite the interest of the public but The First Emperor has exceeded our expectations in every way," Neil MacGregor, the director of the British Museum, told The Daily Telegraph.

After queues formed at 7.30am outside the museum most days, curators said they intend to extend opening hours until midnight shortly after Christmas and to 24 hours before the show's April closure, according to the newspaper.

Some visitors turned up as early as 5am for the chance to see the 20 life-size sculptures from the 2,200-year-old burial site.

After 500,000 bookings were snapped up in a matter of days, 500 tickets are released each morning at 9:15 am to an onslaught of visitors.

The surging tide of interest has the terracotta warriors on course to become one of the most popular in the museum's history - eclipsed only by the 1.7 million visitors who flocked 35 years ago to see the famous Tutankhamun show, when the treasures of the 18th Dynasty boy pharaoh's tomb were first seen in Britain.

Though China has loaned only a fraction of the thousands of warriors dug up from pits close to Emperor Qin's tomb at Xi'an, they have caused huge excitement.

"He created modern China that became for centuries the most powerful nation in the world - something that is happening once more," exhibition co-curator Carol Michaelson, recently told China Daily.

Qin's tomb spans 56 sq km and took about 35 years to build.