Amazon.com Inc said it has extended the order deadline on one of its Christmas shipping options as it seeks to stay competitive in a holiday season that has seen more retailers offer free shipping.

Amazon will let customers place orders as late as December 19 with delivery by Christmas in its Free Super Saver Shipping program, which is available on orders of $25 and more.

According to a survey by Big Research for the National Retail Federation, 87 percent of retailers have a standard shipping deadline of December 20 at the latest for delivery by December 25.

To draw shoppers and compete with Amazon, the world's largest online retailer, more chains are offering free shipping or lowering the minimum size to get free shipping.

For example Nordstrom Inc started offering free shipping with no conditions this summer, while Macy's Inc lowered its free shipping threshold on all online purchases to $75 for Cyber Monday, a major day for e-commerce sales that fell on November 28 this year.

(Reporting by Phil Wahba, editing by Dave Zimmerman)

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