British Prime Minister David Cameron faced demands Wednesday for the return of priceless artefacts looted from Beijing in the 19th century, on the last day of his visit to China.

Cameron travelled to the southwestern city of Chengdu on the third day of what embassy officials said was the largest ever British trade mission to the country.

British officials say deals worth 5.6 billion pounds ($9.2 billion) have been signed so far on the trip, but Cameron has been derided by both Chinese state-run media and the country's sharp-tongued Internet users.

The prime minister last Friday set up his own microblogging page on Sina Weibo, China's version of Twitter, attracting more than 260,000 followers by Wednesday evening.

He invited netizens to ask questions, saying he would aim to reply during the visit.

One of the most popular questions was posted by a prominent Chinese think-tank, the China Center for International Economic Exchanges, which is headed by former vice-premier Zeng Peiyan and includes many top government officials and leading economists among its members.

"When will Britain return the illegally plundered artefacts?" the organisation asked, referring to 23,000 items in the British Museum which it says were looted by the British army.

The British were part of the Eight-Nation Alliance that put down the Boxer Rebellion at the end of the 19th century, a popular uprising against the incursion of European imperial powers in China.

To the Chinese, the ransacking of the Forbidden City, and the earlier destruction of the Old Summer Palace in Beijing in 1860 -- about which one British officer wrote: "You can scarcely imagine the beauty and magnificence of the places we burnt. It made one's heart sore to burn them" -- remain key symbols of how the country was once dominated by foreign powers.

Even now the ruling Communist party appeals to nationalism to bolster its popularity.

Foreign ministry spokesman Hong Lei told reporters Wednesday: "The relevant issue is related to the past history of China as well as the feelings of the Chinese people.

"We hope that relevant countries and authorities and people can respect the Chinese people's feelings and take a responsible and friendly measure on the relevant issue."

Asked whether China was asking for the treasures to be returned, he said: "Relevant Chinese authorities are in communication with the government authorities of relevant countries."

The Department for Culture, Media & Sport in London said the "UK enjoys excellent cultural relations with China", adding: "Questions concerning Chinese items in museum collections are for the trustees or governing authorities of those collections to respond to and the Government does not intervene."

Britain has consistently rejected requests from other countries to return artefacts such as the Elgin Marbles.

The British Museum argues the objects are part of world heritage and are more accessible to visitors in London.

Beijing was outraged by Cameron's meeting with the Dalai Lama -- whom it condemns as a dangerous separatist -- last year, which led to a diplomatic deep-freeze between the two nations.

Despite the trip being billed as a trade mission, it has widely been seen as an attempt to repair some of the damage caused to China-British relations.

But a leading state newspaper launched an attack on Cameron Tuesday, saying in an editorial headlined "China won't fall for Cameron's 'sincerity'" that Britain should recognise it is not a major power but "just an old European country apt for travel and study".

The prime minister has taken more than 100 businesspeople with him to China, including the heads of Jaguar Land Rover, Rolls Royce and Royal Dutch Shell and the chief executive of the London Stock Exchange.