Lego has been working hard to build its brand in China. Last week brought news that a Legoland theme park would go up in Shanghai. There's also a Chinese Lego factory in the works, which will produce toys for families hoping the interlocking bricks can teach their kids about creativity and problem-solving -- two skills China's schools are often criticized for neglecting.

Meanwhile, Lego is also said to be preparing a marketing push in China, where Lego knockoffs are more familiar to most consumers than the original brand. In conversations with Ad Age, execs from multiple agencies described working on Lego's creative and strategic challenge: How can the brand make an emotional connection with Chinese parents who have no fond memories of playing with Legos themselves as kids?

To sum up, it's an important moment for Lego in China. And things just took an odd turn.

Artist and activist Ai Weiwei, a frequent critic of Chinese authorities, wrote an Instagram post Sunday describing a project for an exhibit in Australia. The artist said he had hoped to use a "large quantity" of Lego bricks for the art, and the museum's curatorial team contacted Lego to place a bulk order.

Mr. Ai said Lego declined to supply the bricks, saying it was against "corporate policy to indicate our approval of any unaffiliated activities outside the Lego licensing program."

Mr. Ai wrote: "As a powerful corporation, Lego is an influential cultural and political actor in the globalized economy with questionable values. Lego's refusal to sell its product to the artist is an act of censorship and discrimination."

The artist posted a photo of Legos in a toilet, with the caption, "We're here to inspire and develop the builders of tomorrow (twitter.com/LEGO_Group.)"

Lego issued a statement saying artists were free to use Legos as they see fit -- though as a company, it refrains "from actively engaging in in or endorsing the use of LEGO bricks in projects or contexts of a political agenda."

"In cases where we receive requests for donations or support for projects - such as the possibility of purchasing LEGO bricks in very large quantities, which is not possible through normal sales channels - where we are made aware that there is a political context, we therefore kindly decline support," the company said.

Mr. Ai is a master of creating buzz, and the protest is making ripples outside China, but it probably won't put off too many Lego customers on the mainland. Though he is China's most famous contemporary artist globally, with 294,000 followers on Twitter, he's not so well-known in his home country. Much of his message is censored in China, where the government blocks internet users from accessing the kinds of sites where they might read about dissident artists: The New York Times, Twitter, Facebook, Google searches and even Instagram.

Those outlets and platforms have refused to back down when it comes to China's requirements for censorship. Other Western companies have been accused of bowing to China. LinkedIn, for example, has censored articles related to the 1989 Tiananmen Square crackdown that were posted in China, as Foreign Policy and others have noted.

But Lego is no internet or media giant with a stake in the discussion over global free speech -- it's just a kids' toy. What does it say that a cheerful childhood brand like Lego can get sucked into the discussion over free expression? Maybe it's the clearest illustration yet of how sensitive and strange things can get for foreign brands in China, even when what the brand sells is child's play.