Online retail giant Amazon announced on Tuesday it would raise its starting wage for US workers to $15 an hour, amid long-standing criticism of low pay, and would advocate for a higher minimum wage nationwide.

The pay raise will apply to 250,000 employees, starting November 1, and to the more than 100,000 seasonal workers the company expects to hire for the holiday shopping season.

Amazon founder and CEO Jeff Bezos said the company — valued at nearly $1 trillion — was heeding complaints about its pay structure.

“We listened to our critics, thought hard about what we wanted to do, and decided we want to lead,” Bezos said in a statement.

Amazon also is encouraging other large US employers to follow its lead and said it would lobby US lawmakers for an increase in the federal minimum wage, currently at only $7.25.

But the company did not say it would push for a US minimum wage of $15 per hour, a long-sought goal of worker advocates. Amazon's pay varies by location, so the increase could be between $3 and $5 an hour depending on the state.

The company — which offers online shoppers an unparalleled combination of ease, speedy delivery and choice that few can match — has faced stinging criticism of its labour practices, including gruelling working conditions and lack of job security.

Senator Bernie Sanders, a fierce Amazon critic who has long campaigned for higher wages as the United States recovers from the Great Recession, hailed the decision, saying Bezos and Amazon were “now leading the way.”

“It could well be, and I think it will be, a shot heard round the world,” Sanders said in remarks at the US Capitol. He called on other companies like Walmart and fast-food retailers to follow suit.

“The bottom line is that in the richest country in the history of the world, we're seeing massive levels of income and wealth inequality. In this country, our standard should be that if you work 40 hours a week you should not be living in poverty.”

Taxes cut, wages flat

White House economic adviser Larry Kudlow said the move was “terrific.” “Good for them. I'm in favour of higher wages,” he told reporters.

Thought Amazon portrays the pay raise as a response to critics, with US unemployment now flirting with historic lows, employers across the country are having difficulty finding enough qualified workers to fill open positions.

Some firms have had to curtail or cancel planned investments as a result. A higher wage may mean Amazon can outbid its competitors for the dwindling supply of available workers.

US department store chain Target announced in September it would raise wages to $15 an hour by 2020. The Walt Disney Company is to begin paying that wage to Disneyland workers in California next year and Disney World employees in Florida by 2021.

The new minimum wage also will apply to employees at high-end grocery store chain Whole Foods, which Amazon acquired last year.

“We intend to advocate for a minimum wage increase that will have a profound impact on the lives of tens of millions of people and families across this country,” Jay Carney, Amazon's head of global corporate affairs, said in the statement.

Amazon employees currently receive support for job training, health coverage, as well as retirement benefits and paid parental leave, the company said.

But, despite the tight US labour market and rising after-tax corporate profits, worker pay overall in the United States has so far risen only sluggishly, leaving it effectively flat when inflation is taken into account.

Furthermore, the boom at online retailers like Amazon has coincided with layoffs and store closures for traditional retailers such as Sears, Macy's, Toys R Us and Kmart. Consumers now increasingly opt for home delivery instead of shopping in person.

President Donald Trump had promoted December's sweeping tax cuts by saying they would boost worker pay and the White House has pointed to bonuses many employers have since offered as evidence of increased prosperity.

Bezos, a frequent target of Trump's criticism, is currently the world's richest man, with a total net worth of $165 billion, largely Microsoft founder Bill Gates, according to Bloomberg.

Shares of Amazon were up 0.2 per cent at $2,008.68 in New York shortly before 1500 GMT.