Ten stadiums in nine different cities are due to either be built or substantially revamped at least a year ahead of the tournament, the first time the world's biggest sporting event has been held in Africa.

In a country which has hundreds of thousands of illegal migrant workers and unemployment estimated to be above 40 per cent, cheap labour is not in short supply.

Authorities in South Africa have repeatedly pledged to meet deadlines set by football's world governing body FIFA, whose president, Sepp Blatter, has voiced concerns that the "picks and shovels" have yet to swing into action.

But leaders of the International Trade Union Confederation (ITUC), here for the annual World Social Forum, want the whistle blown on contractors who cut corners to get the job done on time and within budget.

"Football is the world's favourite game. There are millions of people who watch an event such as the World Cup but what the people have no idea about is how the stadiums are constructed," said Andrea Maksimovic, international co-ordinator of a body which groups 306 unions from around the world.

"Forty-six per cent of the people in South Africa have no work. South Africa expects the World Cup will give work to 300,OOO people so it's an important asset."

The ITUC said football fans from around the world need to be prepared to put pressure on all parties to ensure that workers are not exploited.

"At the moment, we want to put pressure on FIFA and the South African governement via the media, to make supporters throughout the world aware of the issue," said ITUC spokesman Mathieu Debroux.

If concerns are unheeded, "other means of pressure" such as a mass petition, would be rolled out, he said.

As well as ensuring that the construction workers are paid a decent wage, the ITUC wants assurances about on-site safety conditions as well the provisions for anyone injured in a work accident.

Maskimovic said the federation is hoping for a more co-operative relationship with the South Africa government, a tripartite alliance which includes the Confederation of South African Trade Unions (COSATU), than it received ahead of the 2004 Olymics in Athens.

"The IOC (International Olympic Committee) didn't play the game," she said.

Authorities in Beijing, venue for the 2008 Olympic Games, last month ordered developers of all new building projects to provide accident insurance to construction workers, after it was reported nearly 700,000 were not covered.

The mayor of Johannesburg said last week that renovations to the FNB stadium, which will host the opening ceremony and final, should start on February 1 and finish by March 2009.

Matches are also due to be played in Cape Town, Durban, Pretoria, Bloemfontein, Port Elizabeth, Rustenburg, Polokwane and Nelspruit.