Officials filed a complaint against retail giant Walmart on Wednesday alleging that the company violated the rights of US workers who took part in protests and strikes.

The National Labour Relations Board said Walmart illegally fired, disciplined or threatened more than 60 employees in 14 states for participating in legally protected activities to complain about wages and working conditions.

The labour board's general counsel first laid out similar charges in November, but held off on filing a complaint while trying to work out a settlement with Walmart.

Those discussions were not successful, government officials said, because the company insisted its actions were legal and justified.

The 2012 protests were organised by union-backed group Our Walmart, which spent years pressing Walmart to raise wages and benefits and make it easier for workers to organise a union.

The group claims the majority of Walmart workers are paid less than $25,000 (£15,300) a year.

If Walmart is found liable, it could be required to award workers back pay and reinstatement and reverse any disciplinary action.

The complaint alleges that in November 2012, Walmart spokesman David Tovar said on TV that there would be "consequences" for workers who engaged in strikes and protests.

Thousands went forward with protests at Walmart stores and the company ultimately fired 19 workers who took part, despite their actions being protected by the National Labour Relations Act.