Global Brand Group (GBG), the firm that manages branding for football's governing body, said in a statement it had noted a British media report about a Chinese factory that makes a figurine of Zakumi, the tournament's green-haired leopard mascot.
"GBG has taken appropriate steps to contract Intertek, the world's largest independent testing, inspection and certification organisation, to conduct an immediate ethical and social compliance audit and inspection of this facility," the statement said.
It said no issues had been raised regarding the company before, but added the manufacturer did not produce any of the other Zakumi toys, merchandise or products.
The manufacture of the mascot and other related toys in China and the accusations of exploitation have angered trade unions in South Africa, where official unemployment stands at nearly 25 percent.
Britain's News of the World reported in January that the factory paid its workers "pitiful" wages and forced them to work in squalid conditions.
Labour federation COSATU, a powerful ally of the ruling African National Congress, demanded an investigation and threatened to disrupt the tournament.
"COSATU has consistently demanded that all World Cup paraphernalia must be manufactured in South Africa so that we can create jobs and inherit a legacy from the tournament which will permanently improve the lives of South African workers," it said in a statement.
"South African consumers, thinking they are making a patriotic gesture by buying the over-priced mascot, are unaware of where it comes from and how it is produced."
A regional branch of the federation said it would call for a boycott of mascot sales and would protest at any FIFA or World Cup event in Cape Town - host of eight matches including a semi-final and a city that has suffered big job losses in its textile sector - "until FIFA behaves ethically".
World Cup organisers have struggled to build excitement among South Africans about the tournament and the union threats could undermine efforts to sell more tickets locally.
GBG said FIFA sought the best manufacturers and distributors for all tournament products.
"As often as possible first choice of production is South Africa, however, in cases where this is impossible international manufacturing partners are considered," it said.
