The Chinese government slapped a $2.4 million tax notice on one of its most prominent artists; one who played a key part in the design of the National Stadium known as the Bird's Nest, where the 2008 Summer Olympics were held.

Artist Ai Weiwei, an outspoken critic of the Communist Party, says the government's action is the latest effort to muzzle him and rein in his criticism of the establishment.

Ai, who was detained without charge for 81 days earlier this year, says the Beijing Local Taxation Bureau has not presented any evidence of tax evasion by him or the company he works for.

They made up this new title ... I'm a designer for the company. I'm not a director, or even a manager. Of course, I know this matter is targeted at me, he told Reuters.

According to the taxation bureau, he is the actual controller of the Beijing Fake Cultural Development Ltd., a company owned by his wife Lu Qing. Rights activists say the government just wants to silence Ai.

According to the China Human Rights Lawyers Concern Group (CHRLCG), Ai is a thorn in the side of the communist regime.

He has demanded democracy in China, criticized government corruption for playing a part in the deaths of thousands of schoolchildren in the 2008 Sichuan earthquake, and supported intellectual Liu Xiaobo, a political prisoner who was awarded the Nobel Peace Prize last December, CHRLCG says.

Ai was detained in April on charges of suspected economic crimes, a development that sparked an international outcry.

Two days before his disappearance, Ai Weiwei spoke to German broadcaster ARD. He warned that people with different minds and voices are being thrown into prison. He said there were two surveillance cameras at his gate entrance, his phone was tapped and every message he sent on the microblog was censored, Emily Lau, Vice-chairperson of CHRLCG, pointed out.