The workers, who complain they underwent "slave-like treatment" at a Mississippi shipyard, demonstrated outside the White House for more than an hour calling for dignity of the employees.

Towards the end of their protest, the workers, in a symbolic rejection of the H2B visa system or the guest worker programme, ripped up the a enlarged xeroxed page of their passport in which their visas had been stamped.

The workers, from among a group of over 100 who walked off their jobs at a Signal International Plant in Pascagula, Mississippwere, were joined by their supporters from several organisations based in Washington DC.

The workers are demanding Congressional investigation of their former employer Signal International, a Northrop Grumman subcontractor that allegedly held them as forced labour, and is already the subject of a criminal human trafficking investigation by the Department of Justice.

As many as 500 Indian welders and pipe-fitters had forked out about USD 20,000 apiece to US and Indian recruiters for false promises of permanent residency in the America, organisers of the protest said.

"Instead they were held in forced labour by Northrop Grumman subcontractor Signal International on 10-month temporary H2B guest worker visas in Gulf Coast shipyards under deplorable conditions," the organisers said.

The US Department of Justice has opened a human trafficking investigation into the case, and Congressman George Miller has called for a detailed documentation about the case from Secretary of Labour Elaine Chao.

The protest at the White House on Monday will be followed by meetings on Capitol Hill where the workers and the representatives will be briefing Congressional staffers on the specifics of what took place at Signal International.

They will also meet members and staff of the Congressional Hispanic Caucus and the Congressional Asia Pacific American Caucus and call for investigation of Signal International.

Meanwhile a legal representative of the Southern Poverty Law Centre has brushed off as "jurisdictional" the rejection of a plea of two Indian workers against Signal by Civil Rights Division of the Justice Department.

In a letter dated March 14, the Civil Rights Division of the Department of Justice told Signal International that it will not be filing a complaint on a breach of practice under '8USC/1324b' related to unfair employment practice.

"Based on its investigation, this office has determined that there is insufficient evidence of reasonable cause to believe the injured parties were discriminated against as prohibited by 8USC/1324b," it said.

"Therefore this office has decided not to file a complaint with the Office of the Chief Administrative Hearing Officer regarding these matter," it added.