ZURICH?Swiss border guards have seized the 18th-century violin of an acclaimed concert musician, Patricia Kopatchinskaja, who could face a huge fine for failing to declare it, authorities said Tuesday.

The 33-year Kopatchinskaja, who was born in Moldova but now lives in Switzerland, was questioned about the violin when she flew into Zurich airport on Saturday, a spokesman for the Swiss federal customs office said.

"The violin was not declared upon entry into Swiss territory," he explained, adding that she risks a fine of up to 700,000 Swiss francs (?488,000, $651,000).

Swiss residents are required to declare purchases abroad of above 300 Swiss francs in order to pay duty and tax.

Kopatchinskaja plays a rare 1741 Italian-made Guanerius del Gesu violin -- the "ex-Carrodus" -- which is on loan to her from the Austrian central bank (OeNB). The instrument has been valued at ?4.5 million ($6.0 million).

It was not immediately clear if she had taken the instrument in and out of the country before.

"We see this as a misunderstanding. It'll all be resolved amicably," a spokesman for the OeNB said Tuesday.

The "ex-Carrodus" is one of a total 36 priceless violins -- including a number of Stradivari -- that the Austrian central bank owns and lends to promising young musicians.

Kopatchinskaja may not have had all the necessary paperwork with her proving that the violin was merely on loan, as she returned home from a concert in Rotterdam, said OeNB spokesman Oliver Huber.

Kopatchinskaja, who also has Austrian nationality, has garnered international awards and critical acclaim in recent years.

She has a packed concert schedule through mid-2010 in Europe and Australia.