AFP - Switzerland initiated contact with the United States over the scheduled visit of Oscar-winning director Roman Polanski to Zurich, a move that led to his arrest, a Swiss Justice Ministry spokesman said Wednesday.

"In September, when we received information that Polanski would be visiting Zurich, we wrote to the American authorities to ask if the warrant was still valid, in order to avoid a pointless arrest," said Folco Galli, confirming media reports.

"This was confirmed and the American authorities sent us the warrant two days later," he told AFP.

Polanski was detained by police acting on a US extradition warrant for 32 year-old child sex offence charges when he flew into Zurich to collect a lifetime achievement award at the Swiss city's film festival on September 26.

The arrest of the fugitive French-Polish film-maker sparked criticism from some quarters. Switzerland has argued that it had to act given its international obligations.

Swiss newswire ATS reported that Bern had contacted US authorities on September 21 about Polanski's imminent visit through a fax marked "urgent" and Washington replied on September 23.

"We did only what we had to. We were obliged by the treaties," said Galli, who sought to dismiss criticism on why the Swiss had acted only now.

Polanski owns a property in Switzerland and regularly spends his holidays here.

"Before, we did not know when he would arrive in Switzerland. We did not have any indication of his presence," Galli argued, pointing out that on this occasion, however, it was clear that Polanski was due to visit.

Swiss media and politicians have speculated that Bern might have been seeking to polish its image in Washington following the recent diplomatic spat with the United States over Swiss banking giant UBS, which was found to have abetted US tax cheats.

Switzerland's top criminal court on Tuesday declined to release Polanski from jail on bail, saying there was a "high" risk that he could flee the country.

Polanski has been regarded as a fugitive by US authorities since he fled the United States in 1978 after admitting to having sex with a 13-year-old girl.