MADRID, Spain — Inditex SA, the world's biggest clothing retailer, is seeking a buyer for 16 Zara stores in Iberia as online purchasing takes off in Spain.

Inditex, owned and founded by Amancio Ortega, the world’s fourth-richest man, is seeking 400 million euros ($472 million) for the stores in a 20-year sale-and-leaseback agreement that would give the buyer the right to vacate the properties after five years, according to a person with knowledge of the matter. Fourteen of the units are in Spain and two in Portugal, the person said, asking not to be identified because the deal is private.

An Inditex official confirmed the potential sale and said it’s part of a strategy to homogenize its leasing strategy. Almost all its stores are operated through leases, the official added. The representative did not confirm the offer price.

Inditex, whose 11.7 billion euros in first-half revenue was boosted by an increase in internet sales, is betting Spain will catch up with the rest of Europe in online purchasing. Last year, 3 percent of Spanish retail sales were done via the internet, compared with 8 percent across Europe and 15 percent in the U.K., according to Aberdeen Standard Investments.

“While Spain has the lowest absorption of internet sales now, it’s expected to have the highest growth rate” in coming years “as cultural attitudes toward online shopping change,” said Andrew Allen, global head of real estate investment research at Aberdeen Standard Investments. “We estimate annual growth in internet purchases of 18 percent per year to 2021 for Spain, versus an average of 12 percent for Europe as a whole.”

The sites up for sale include the Zara women’s fashion store in Calle Preciados, Madrid’s most expensive high street in terms of retail rents. Inditex was founded in 1963 as a family-run workshop making affordable clothing for women and now has more than 7,000 stores in 94 countries, according to the company’s website.

By Sharon Smyth and Rodrigo Orihuela; editors: Neil Callanan and Paul Armstrong.