The managers of the Old Summer Palace in Beijing, looted by British and French troops in the 19th century, are threatening legal action over a Chinese movie studio's sprawling $5 billion replica, state media said.

In 2007, Hengdian World Studios, the world's largest outdoor film studio, announced it planned to build a multi-billion-dollar replica of Beijing's Old Summer Palace at its headquarters some 1,500 kilometres south of the Chinese capital.

The 18th-century original in Beijing's northwest served as a retreat for China's emperors, with lavish gardens, fountains and pavilions, but was pillaged by British and French troops in 1860 during the Second Opium War.

The event has long been regarded as one of the most humiliating episodes of Chinese history, and Communist authorities stress it as an example of the country's victimisation by foreign powers.

Parts of the new version are finally scheduled to open next month, but the project has been sharply criticised by the stewards of the former imperial complex, who said that the 400-hectare (990-acre) site is "unique and cannot be replicated".

"The construction and development of the site should be planned by authoritative national organisations, and any replication of it should reach certain standards," the palace's administrative office told China's official Xinhua news agency Sunday.

Xinhua said potential legal action centred on intellectual property rights, without giving details.

Hengdian founder Xu Wenrong defended the project, telling the agency that it was an effort to educate China's younger generation about China's past rather than simply build a reproduction of the site.

Hengdian World Studios has already built a full-scale replica of Beijing's Forbidden City. Yet the Old Summer Palace, or Yuanmingyuan, project has attracted controversy due to its place in Chinese history.

The destruction was in response to China's capture, torture and killing of members of a British and French delegation.

Beijing has waged a persistent campaign to retrieve 1.5 million relics it estimates were taken from the imperial complex at the time.

- 'Written in blood' -

When the film studio announced the project in 2007, experts and others were sharply critical, arguing the money would be better spent preserving surviving cultural relics than recreating long-lost ones.

"The replica is unnecessary because the Yuanmingyuan was destroyed by the Allied Forces and the present day ruins serve as a testimony to that period of humiliating history," cultural relics expert Ruan Yisan had told Xinhua.

In the wake of the latest row, some in China rallied to defend the movie studio, arguing that the project will strengthen public understanding of China's history.

"The Old Summer Palace was built at the cost of the whole nation but open to the royal family only; if the recreation in the movie town opens to the public, it will help more people know about our history and engage with the past," said Yang Jianhua, a researcher at Zhejiang Academy of Social Sciences, according to the China Daily.

On China's popular online social networks, some users called the Old Summer Palace's claims laughable.

"Historical relics have no 'intellectual property' rights," wrote one user of Sina Weibo, a Chinese version of Twitter, on Monday. "If you carve a statue of Confucius, Washington, or any other figure from hundreds or thousands of years ago, is that a violation of their rights?"

Others called for the new project to be halted.

"I think they shouldn't rebuild it," a Sina Weibo user wrote. "That history is written in blood. A dilapidated Yuanmingyuan is better able to remind us of that humiliating chapter of history."