Convergys Corp, an American call-centre services and billing software firm, on Wednesday unveiled an ambitious plan to more than double its staff in India to 6,500 in about a year, as it boosts operations in countries with low staff costs.

Convergys, which has about 3,000 people working out of its centre in Gurgaon outside Delhi, has launched its second unit in Bangalore.

"This is only the beginning of our expansion plan in India," John Freker, president of the firm's call-centre business, told a news conference. He did not provide any financial details.

"We can see us growing up to 20,000 people in India within the next three years," said Jean-Marc Hauducoeur, senior vice-president of Convergys' offshore operations.

Convergys' hiring binge comes when global giants are rapidly setting up and expanding their back-office services units in India amid a stubborn economic slowdown, lured by the country's vast pool of low-cost English-speaking graduates and engineers.

At the same time, Indian companies are also emerging as one-stop shops combining software with back-office services like payroll processing and customer support.

"We see demand growing very fast, especially from the United Kingdom, looking to outsource business to India," Freker said.

Convergys employs more than 44,000 people across the world and has roughly 400 clients in sectors including telecommunications and financial services.

Computer-maker Dell and media giant AOL Time-Warner have in the past few years joined General Electric and American Express in setting up huge back-office services units in India.