A campaign calling for the largest retailer and employer in the US to reform working practices will kick off on Thursday with a nationwide Day of Action.

Organisers are hoping that thousands of people will lobby Wal-Mart shops around the country on the first day of The People's Campaign - Justice @ Wal-Mart.

[This is] an effort to discredit the company

Wal-Mart spokesman Bill Wertz

Wal-Mart spokesman Bill Wertz has rejected the action, saying he is confident customers will dismiss the campaign as "an effort to discredit the company".

Wal-Mart - which is also the largest retailer in the world - is under fire from labour organisations which accuse it of implementing and exporting bad labour practices.

"The biggest corporation in America today has a business plan that lowers standards, first among its own employees and ultimately for all Americans," John Sweeney, president of US labour federation AFL-CIO, ahead of the campaign.

Protesters are hoping the public will lobby Wal-Mart stores

"We are determined to help Wal-Mart find a better way."

Wal-Mart's spokesman said that while it rejected the campaign it would not ignore the claims.

"Any company takes seriously criticism of its character and integrity," he said.

The United Food and Commercial Workers International Union (UFCW), which is spearheading The People's Campaign, says at its core is a coalition of 33 organisations, including labour, consumer, student and faith groups.

'American values'

The campaign will range from lawsuits and consumer boycotts and prayer vigils.

According to the campaigners, Wal-Mart has fallen foul of labour watchdogs on a number of counts, including:

• paying low wages that often preclude employees taking out health insurance
• preventing employees from joining unions
• imposing lax safety and compensation standards
• employing predatory pricing tactics to close down small local competitors.

The union is calling for Wal-Mart to endorse a list of six "American values" in its businesses practices.

Campaigners say that a particular concern is that the company - whose last annual sales were worth $200bn - is now beginning to export its practices overseas by demanding that suppliers reduce wages and benefits in order to cut costs.

"If Wal-Mart buys in countries where child labour is prevalent, producers shift investment in the pursuit of the lowest wages and the most easily exploited labour," says UFCW president Doug Dority.

'Browbeaten' employees

Mr Wertz says that fear is unfounded. Although he had not yet seen the list of ethics, "we're already following a number of the principles it states", he said.

He cited the company's "very strict policy against child, forced and slave labour".

With over one million workers, Wal-Mart has often been a target for union activists, but Gretchen Adams, a former Wal-Mart store manager who now works for the UFCW, says that employees are "browbeaten" into rejecting unionisation.

But Mr Wertz counters that employees do not feel they require union representation.

"Our associates [employees] realise their partnership with the company makes third-party representation unnecessary," he says.

The company spokesman insisted that Wal-Mart had "very competitive benefits and very competitive wages".