French customs officials seized a Picasso painting worth 25 million euros ($27 million) over concerns it could be permanently removed from Spain in defiance of an export ban, officials said on Tuesday.

The 1906 "Head of a Young Woman", owned by Spanish banker Jaime Botin, was confiscated on July 31 from a boat moored in the Corsican port of Calvi, the customs directorate said in a statement.

Officers boarded the vessel after French authorities in Corsica received a request for authorisation to export the painting to Switzerland, according to a spokesman.

It was not known how the painting turned up in Calvi. In May, Spain's High Court blocked a bid by Botin, a former vice-chairman of banking group Santander, to export the Picasso to London following an application by auctioneer Christie's.

In its ruling, the court declared the painting a Spanish national treasure.

French customs said they had impounded the painting pending an expected request for its return to Spain.