(Reuters) - Hundreds of delivery drivers for e-commerce giant Amazon.com (NASDAQ:AMZN) have joined the International Brotherhood of Teamsters, seeking improved wages, working conditions and safety standards, the labor union said on Monday.

Workers across three Delivery Service Partners (DSP) in Queens, New York are demanding Amazon recognize their union and negotiate a Teamsters contract, the union said.

Unionization efforts have been picking up in recent years as large number of contract workers across the country bargain with Amazon for better working conditions, consistent schedules and reasonable workloads.

Amazon did not immediately respond to a Reuters request for comment.

The organization efforts in New York mirror other workers in Palmdale, California and Skokie, Illinois who are also on strike making similar demands.

Amazon said last week it would increase the compensation to its DSPs through a $660 million investment over the next year.

Earlier this month, a National Labor Relations Board prosecutor concluded that Amazon should be held jointly liable with a contractor for allegedly using unlawful tactics to discourage delivery drivers in Atlanta from unionizing.