Dec 19 (Reuters) - Amazon.com workers at seven U.S. facilities walked off the job early on Thursday during the holiday shopping rush, aiming to pressure the retailer into contract talks with their union.

Warehouse workers in cities including New York, Atlanta and San Francisco are taking part in the "largest" strike against Amazon, said the International Brotherhood of Teamsters, which represents about 10,000 workers at 10 of the firm's facilities.
The company, however, said it does not expect any effect on its operations during one of the busiest times of the year.

Unions represent only about 1% of the hourly workforce of Amazon, the world's second-largest private employer after Walmart, and it has multiple locations in many metro areas.
The Teamsters had given Amazon a Dec. 15 deadline to begin negotiations and warehouse workers had recently voted to authorize a strike.

"If your package is delayed during the holidays, you can blame Amazon's insatiable greed," Teamsters' General President Sean O'Brien said late on Wednesday.