Protesters gathered outside the Chinese embassy in west London today to callfor a ban on the country's booming trade in ivory from elephant tusks.
Chinese demand for ivory is claimed to be driving the slaughter ofan estimated 40,000 African elephants every year.
With the animals in danger of extinction, wildlife charities are asking China to ban the ivory trade, destroy all its ivory stocks and close ivory carving factories.
Ornaments made from ivory are a traditional symbol of wealth and status in China.
"It's no secret that China holds the key to saving the planet's elephants, or making them extinct in the very near future.
"Although it was very encouraging to see China destroy six tonnes of seized ivory in the early part of this year, it's time now for China to take a much bigger leap forward and send a clear statement to the world - by banning the sale of ivory once and for all."
A spokesperson for the Mayor of London has defended criticism of the cost of Mr Johnson's October trip to China claiming the "costs have already been reimbursed many times over" in investment and trade deals.
“The costs of the Mayor’s trip to China have already been reimbursed many times over in terms of deals announced by businesses he met and lobbied on the visit that will provide hundreds of millions of pounds of investment in London," a spokesperson for the Mayor of London said.
"Those deals are part of a huge wave of Chinese investment and confidence in the capital. The objective of the Mayor’s visit was to position London as the city of choice for Chinese business, tourists, entrepreneurs and students with a view to attracting the jobs and growth to London
"The objective of the Mayor’s visit was to position London as the city of choice for Chinese business, tourists, entrepreneurs and students with a view to attracting the jobs and growth to London that are already in evidence in the deals announced since the Mayor returned."
London Mayor Boris Johnson's trade trip to China cost over £65,000, a Freedom of Information Request has revealed.
The total cost of the week-long trip was £65,653.42, during which the Mayor held meetings with companies and politicians in a bid to attract investment to London.
Over £50,000 was spent by City Hall on travel, with £1,456 on eight business class train tickets, £11,532 on accommodation, £2,645.92 on incidental expenses and £1043 on visas, the Huffington Post reported.
The Mayor took nine City Hall officials, eight business representatives and seven journalists for the trip.
The Mayor of London has visited the 'forbidden city' in Beijing as part of his official trade tour of China. Boris Johnson is hoping to encourage billions of pounds of investment in the capital from Chinese businesses.
One such company is ABP, which is redeveloping the capital's Royal Albert Dock. Today the firm's boss told ITV News that the money coming from China was good for British society. Our China Correspondent Angus Walker reports.
Boris Johnson celebrated an agreement for British designer Thomas Heatherwick to build two Beijing underground stations by taking a trip on the network himself. London's Mayor said Britain remained competitive internationally in creative industries, like design and fashion.
Thomas Heatherwick, who designed the cauldron that featured in the London 2012 Olympics opening ceremony, could also be commissioned to build an entire line for Beijing's underground, which could include 15 to 20 stations.