Anish Kapoor Sculpture

Anish Kapoor dedicates Leviathan sculpture to Ai Weiwei

Call goes out for museums and galleries to close for a day in sympathy for missing Chinese artist

Anish Kapoor has dedicated his largest ever artwork - a truly enormous cathedral-like space made from inflated PVC - to the missing Chinese artist Ai Weiwei.

The sculptor called for a worldwide day of action where museums and galleries close for one day in sympathy for the plight of his fellow artist. "Why not?" he asked.

Ai, whose sunflower seeds work in Tate Modern's Turbine Hall closed at the weekend, has been missing for about a month, in the hands of the Chinese authorities. He had not been heard from, nor charged with any offence.

"I've never met Ai Weiwei but he's a colleague, an artist," said Kapoor. "In a very simple way he is heroically recording human existence. All he's done is to record death by administration, death by corruption, inefficiency. I don't even think he's pointing that sharp a finger, frankly."It is more than a month that he's been completely disappeared. It is a true tragedy. Accuse him of something. Give him a lawyer. Let him defend himself... The state is not threatened by artists.

Kapoor was speaking at the opening of the Monumenta exhibition in Paris's Grand Palais - a commission similar to the Turbine Hall in that it is filling a vast space, this time with the added trickiness of having glass windows all around.

"This is a terror of a space, probably much more difficult than the Turbine Hall," Kapoor said. "It's three times the size, huge horizontally and vertically and above all the light is a killer. It's almost brighter than it is outside."

What Kapoor has created he's called Leviathan, a 35-metre tall work - inflated, it's 13,500 square metres.

Visitors first of all walk inside it, like going into the belly of a whale or a cathedral with three chambers veering off it. Then outside you see what it actually is - four connected balloon-type structures. Something from a science fiction film, perhaps, that's taken refuge in this grand 19th-century glass building by the Seine.

Kapoor and his team have spent the past week inflating the work and there was no trial run. "We had one shot," he said. "Doing a project like this is about taking a risk."

The work will stay up until 23 June before it is gently deflated like a bouncy castle at the end of a fair. A very big castle with absolutely no bouncing allowed. The PVC alone weighs 18 tonnes and will be folded up into three parcels when it's let down - a 90 minute process.

Kapoor is known for his supersize works from the trumpet like Marsyas at Tate Modern in 2002 to Temenos, his enormous net-like sculpture in Middlesbrough. It is an impressive piece of design and engineering. "It is a perfect bit of tailoring," said Kapoor. "A millimetre out and there are wrinkles and wrinkles aren't allowed."

The work is also pan-European. The initial computer work was done in England and then the PVC was cut in Germany, assembled in Italy and set up by a Czech crew in Paris. Kapoor is the fourth artist to take on the Monumenta commission, following Anselm Kiefer, Richard Serra and Christian Boltanski.

Dedicating the work to Ai reflects mounting concern for the artist and continuing pressure on the Chinese authorities to explain why he is missing.

Tomorrow outdoor sculptures by Ai will be opened to the public at Somerset House in London, while on Friday a survey of his work will be held at the gallery which represents him in London, the Lisson - an exhibition that was planned with the artist last year. Greg Hilty, the director of the Lisson, said: "The response to what's happened to Ai Weiwei from the artistic and wider community has been incredible. It just keeps growing."

Hilty feared the situation may put up cultural walls between China and the west. "The idea of some worldwide cultural gesture is absolutely appropriate and the idea of closing is the right one because that's what this is about. If you imprison artists then you don't have them."

Anish Kapoor's Leviathan is at the Grand Palais, Paris, until 23 June