Chinese artist Ai Weiwei says authorities have razed his Beijing studio.

The frequent government critic said on his Instagram account the demolition began on Friday without any prior notice.

He posted videos of an excavator smashing the windows of his Zuoyou studio site.

The studio in the northeast Beijing suburbs has been Ai's primary work space since 2006, although he has mostly been based in Europe in recent years.

It is unclear whether the demolition is targeting Ai specifically.

Beijing authorities have demolished large swaths of the suburbs in the past year in a building safety campaign, but typically give at least several days' notice.

Ai, who has called attention to human rights violations and government corruption in China, was held for more than two months in 2011 on alleged tax evasion.