A British art dealer was sentenced to up to 12 years in prison by a US judge Tuesday for stealing millions of dollars from the sales of paintings, including a Picasso.

Timothy Sammons, who operated out of New York, London and Zurich, defrauded at least four collectors of between $10 million and $30 million by selling valuable artworks and then pocketing the money himself.

The 63-year-old had pleaded guilty to 15 counts of grand larceny and fraud at a hearing in New York earlier this month.

On Tuesday, Justice Ann Scherzer told Sammons that he would serve between four and 12 years in jail.

"For years, the defendant peddled a deceitful, money-spinning scheme, garnering the trust of prospective buyers and sellers only to defraud them of millions and use the ill-gotten gains to fund his lavish lifestyle," said prosecutor Cyrus R. Vance.

Between 2010 and 2015 Sammons brokered the sales of several pieces of highly sought-after art, including Picasso's Buste de Femme and Marc Chagall's Reverie as well as works by Rene Magritte and others.

He failed to hand over the proceeds to the sellers, either by not telling them the artwork had been sold or misleading them about the timing of the sale. 

Sammons, who previously worked for Sotheby's in New York, spent the money on first-class flights and private club memberships. He also used it to pay back debts owed to other victims.

Sammons put up some paintings as collateral to get loans from a personal finance company. When he failed to repay the debts, the paintings were sold at discounted prices.

"When brokering the sales of high-priced, one-of-a-kind paintings, Timothy Sammons had lying, scamming, and stealing down to a fine art," said Vance, the Manhattan district attorney.