In a statement, Lego said it had a policy of refusing to endorse the use of Lego bricks for projects with a "political agenda".
"We refrain, on a global level, from actively engaging in or endorsing the use of Lego bricks in projects or contexts of a political agenda," a statement provided to the ABC read.
"This principle is not new from the LEGO Group."
In a message posted on Instagram, the Chinese activist said he believed Lego's decision was influenced by newly announced plans to build a Legoland park in Shanghai.
In September Lego refused Ai Weiwei Studio's request for a bulk order of Legos to create artwork to be shown at the National Gallery of Victoria as "they cannot approve the use of Legos for political works." On Oct 21, a British firm formally announced that it will open a new Legoland in Shanghai as one of the many deals of the U.K.-China "Golden Era." A photo posted by Ai Weiwei (@aiww) on Oct 23, 2015 at 6:04am PDT
British firm Merlin Entertainments said on October 21 that it would be partnering with Chinese firm, China Media Capital to build the park.
Lego is expanding its presence in China to boost demand for its product in the Asian market.
The company said it plans to have its first China-based factory in Jiaxing, 100 kilometres from Shanghai, operational by 2017.
The bulk order of Lego bricks would have contributed to an artwork to be exhibited at the National Gallery of Victoria.
Ai has used Lego in his political artworks previously, including in an exhibition last year called ‘Trace’.
Large carpets of Lego blocks were used to construct pixelated portraits of 175 prisoners of conscience, among them Nelson Mandela, Edward Snowden and Chelsea Manning.
The Beijing-born artist shot to international prominence when he went missing for 81 days in 2011 on allegations of economic crimes, prompting an international campaign calling for his release.
He has since been granted a three-year German visa after being detained numerous times in China.
Ai has been vocal in his criticism of the Chinese government’s handling of the Sichuan earthquake and the Beijing Olympic Games, highlighting issues of democracy and human rights.
