(Reuters) -Amazon.com said on Thursday it will increase the compensation to its Delivery Service Partners (DSP) through a $660 million investment over the next year.Amazon's package delivery is done mostly by DSPs, small businesses that employ drivers and set their salaries.

As a result of the investment, Amazon ( AMZN ) expects the national average earnings for drivers to increase by at least another $1.50 to nearly $22 per hour, depending on the location, which represents a 7% increase over last year.

The funding is part of an incremental investment of over $2.1 billion in the DSP program, bringing its total investment to $12.3 billion over the last six years.

Amazon ( AMZN ) will also launch an app for the DSP's drivers, where they will be able to access up to 50% of accrued wages before their payday.

The ecommerce giant said it will use AI to identify risk characteristics for 200 million roads and provide 18 million safety cues for drivers by the end of this year.

Amazon's ( AMZN ) investments come days after a National Labor Relations Board prosecutor concluded that the company should be held jointly liable with a contractor for allegedly using unlawful tactics to discourage delivery drivers in Atlanta from unionizing.

Another regional director from the NLRB in Los Angeles concluded that Amazon ( AMZN ) should be considered a so-called "joint employer" of a separate contractor's employees and thus be obliged to negotiate with unions.

The company, however, has said in the past that it does not exert enough control over contractors' drivers to be considered their joint employer.