PARIS (AFP) - Move over Popemobile, make way for the "Popebike": a Harley-Davidson that briefly belonged to Pope Francis and is being auctioned off in Paris on Thursday has already garnered significant advance interest from around the world.

A day ahead of the much-anticipated sale, Bonhams auction house said it had received some 30 purchase orders worth much more than the 12,000 to 15,000 euro (S$20,000 to S$25,700) valuation of the 1,585cc Dyna Super Glide signed by the pontiff himself.

"Unsurprisingly, there is real interest. The sale of the pope's motorbike promises to be hotly contested. The result will no doubt live up to its first owner. The papal signature, a first on a vehicle, makes this sale unique," Bonhams France said.

Harley-Davidson gave the bike to the pope in June to mark the 110th anniversary of the United States (US) motorbike maker.

The pope donated the Harley in November to the Roman Catholic charity Caritas Roma and the funds from the sale will go towards the restoration of its hostel and soup kitchen based at Rome's Termini railway station.

Pope Francis, 77, is not thought to have ridden the Harley, a brand well known for its use by motorbike gangs including the "Hells Angels".

The famously humble pontiff is more of a fan of buses. He opted to ride one the day after his election last year instead of taking a limousine, and regularly used them in his homeland Argentina instead of taxis.

The bike is already on show at the Grand Palais in Paris - where the auction takes place on Thursday - among hundreds of other iconic vehicles such as Rolls-Royces and Cadillacs.