It had been advertised as “Banksy unauthorised”, a retrospective of 58 of the street artist’s most famous works, put on display in an empty supermarket in a swanky part of Brussels.

On Thursday night, a Belgian court proved just how unauthorised the exhibition may have been by ordering bailiffs to seize the art, valued at over £12m.

After five hours, and some careful handling, the pieces, including a version of the famous stencil mural Girl With Balloon, were driven away at midnight to an unidentified secure location, where they will sit out of the public eye until another court hearing in January.

Stanislas Eskenazi, a lawyer for Strokar Inside, the not-for-profit organisation putting on the exhibition in the former Delhaize supermarket, said his clients had been caught up in a “crazy story”, pitting a former Banksy manager against a German go-between company whose previous speciality was selling meat.

“My clients are two very nice people,” Eskenazi said. “And they have been shitting it.”

The Banksy collection was offered to the gallery in the suburb of Ixelles in the south of Brussels by a German-based company called On Entertainment, Eskenazi said.

The firm in Neuss said it had been running an exhibition in Berlin, but wanted to bring the show to the Belgian capital.

The show has been on a world tour organised by Steve Lazarides, a former gallery owner, who is said by some to have been the first to launch the secretive Bristol street artist into the public eye. Banksy had not given Lazarides his consent, hence the eye-catching “unauthorised” tag added to the name of the exhibition.

Last week, however, lawyers from Mishcon de Reya, a Mayfair law firm, came knocking on the door of Strokar Inside, and according to court papers, accused the gallery of illegally holding the art. It was Lazarides’ property, they said, and On Entertainment had no right to bring it to Belgium.

“My clients didn’t know what to think”, said Eskenazi. “They had thought there was something a bit weird about it earlier on. They had asked two things of On Entertainment: that they had the rights to put the pieces on display, and that they were insured. This was €15m [£13.3m] worth of art. My clients did not have the money for that so they were just renting out the space.”

Eskenazi said he was told by Mishcon de Reya that On Entertainment did not have any right to move the art from Berlin and that it should be immediately handed over to Lazarides.

After a weekend of correspondence Strokar Inside decided that they did not want to be caught in the middle and went to court to have the art seized until Lazarides and On Entertainment could thrash out their dispute in court.

“When my clients didn’t get reassurance from On Entertainment that the art was insured, they just wanted to get out this situation”, said Eskenazi. “We also by then had discovered that the company had recently been involved in selling meat. It was very strange.”

The Brussels court agreed, ruling that “the disputed works do indeed appear to be exposed, without the agreement of the legitimate holders of rights over them, in the premises, where they do not appear to be regularly insured, and that there are reasons that it would seem necessary to secure them as quickly as possible”.

“English lawyers can be very aggressive,” Eskenazi said. “We don’t know who has the rights to display the art and we don’t want to know. We don’t want anything to do with it. My clients were freaking out.”

A second court hearing to hear the rival claims is set for January. A spokesman for Lazinc, the company founded by Lazarides in 2006, declined to comment.

Quite what Banksy himself thinks of the drama is not known. He did, however, over the summer offer some criticism of his one-time friend and manager after discovering the prices being charged to fans.

In an Instagram post showing a screen-grabbed text message conversation, he voiced dismay over the Moscow leg of the tour after being told that patrons were being charged a £20 entry fee. “What the hell is that?” he said. “It’s got nothing to do with me… I don’t charge people to see my art unless there’s a fairground wheel.”

Urged to put out a press release disavowing Lazarides’ exploitation of his art, the artist had responded: “Hmm – not sure I’m the best person to complain about people putting up pictures without getting permission.”