In an industrial park near Singapore's harbour, a group of people spray-paint a wall with the bright colours and rebellious swirls of graffiti.

Under other circumstances, their action would lead to prompt arrest. But the "taggers" are artists taking part in a performance highlighting the urban art form.

Graffiti is seriously frowned upon in Singapore. Last year, a Swiss man was jailed and caned for vandalism after he spray-painted a subway train.

But the perception in the city-state that graffiti is nothing more than vandalism by wayward youth is changing, thanks in part to art festivals like the one at the industrial estate, part of the Voilah! French Festival Singapore.

"There is still a sense of graffiti as anti-social behaviour, but when people see it in a gallery, it becomes an artistic endeavor," said Howard Rutkowski who helped organise the event and exhibited 72 pieces of graffiti art on canvas at a gallery in the estate.

Even among aficionados, though, the purpose of the art form is open to debate.

Two years ago, a group of graffiti artists found themselves barred from the only government-sanctioned arena where spray painting is allowed, a youth park in a shopping district.

The reason given was that they wanted to spray paint messages in support of children victimised by the Palestine-Israel conflict.

"Graffiti is not political, it is a form of expression, something to be explored in the city," said Yann Lazou, one of the Frenchmen painting the wall in the industrial park.

Graffiti art is proving popular.

One piece sold for 7,500 euros at the exhibition, snapped up by a European collector. Two pieces by Dubai-based graffiti artists Sya and Bow went for about S$2,000 ($1,540) each at a separate event.

But even as graffiti gains among collectors, its acceptance appears to be qualified.

"Graffiti on a cardboard or canvas as a form of painting is a piece of art. But graffiti painting cars or walls is irresponsible," said Singaporean art collector Elson Ng.

Singapore graffiti artist Shah Rizzal, who also took part in the event, hopes his country will some day grow to view his work favourably and embrace it on a larger scale and more openly.

"Perhaps graffiti will one day grow beyond the gallery and infiltrate the institutional space," he said.

But that may take some more time. Even for the event, the artists didn't paint on a real wall but on a special, temporary one erected for the performance.