Media playback is unsupported on your device Media caption 'They said they would come and smash our windows'

The dissident Chinese artist Ai Weiwei says the authorities in Beijing have demolished his studio there.

In a series of clips on Instagram showing the former factory being torn down, Ai said that he had been given no notice of the decision.

Another of his studios in Shanghai was destroyed in 2011. He also said at that time he had received no warning.

The 60-year-old has lived in Germany since leaving China in 2015. He is a strong critic of China's government.

On Instagram Ai said "farewell" to the space, which he had used since 2006.

One of Ai's assistants, Gang Ra, told the AFP new agency that the rental contract for the building had ended last year but that it "simply wasn't possible" to move out at the time because of the amount of works still present.

He said that they had been told that the move would need to take place within a matter of days, but added that they had not been warned when the demolition would begin.

The son of one of China's most famous poets, Ai designed Beijing's 'Bird's Nest' stadium for the 2008 Olympics but has since become an outspoken critic of the Chinese government.

He was arrested for several months in 2011 and had his passport confiscated. He then moved to Berlin in 2015.