It is a vanishing trick teenage wizard Harry Potter would be proud of.

After nightfall, silver tabby Knut slipped out of his Brighton home for a typical night on the tiles.

But in a mystery which whiffs of the work of the evil Voldemort in a Harry Potter book, the tom never returned.

His loss has upset owner Ulrike Darbon but will also be a blow to the makers of the eagerly awaited multi-million pound Harry Potter film to be released in November.

For Knut, pronounced Canute like the king who tried to turn back the tide, is no ordinary moggie. He is one of the four-legged stars of the Harry Potter film based on the best-selling children's books by JK Rowling.

Ulrike, of Railway Street, Brighton, said: "He might be a star but to us he's just our cat and we want him back.

"He has never spent more than a night away from home before and I keep thinking he will be waiting for his dinner when I get back from work."

Knut spent a month on location at Durham Cathedral on the secret set with the Harry Potter cast. His role is the feline alter-ego of Professor McGonagall, Harry's teacher at Hogwarts School of Witchcraft and Wizardy played by Dame Maggie Smith. When the professor magically transforms herself into a cat to stalk the corridors of the school, Dame Maggie takes time out and Knut graces the screen.

He was chosen for the part after beating off competition from other silver tabbies across the country.

Sets for the new film have been closely guarded to stop any details leaking out with a short trailer released on the internet providing the world's only glimpse of the film so far.

Yesterday Warner Brothers refused to release any details about Knut's role but a spokesman said he was upset to hear of his plight.

He said: "We want to keep the magic alive for the children so it is not spoilt for them."

Silver tabbies have become popular since one appeared in a television ad for Bacardi Breezers.

Ulrike said: "I used to laugh when Knut went out at 10pm because we said he could be going clubbing like George on the television.

"Breeders are saying there has been too much demand for the cats since the advert so I am worried he could have been stolen."

Anyone who spots Knut should phone Ulrike Darbon on 01273 323345.