The offices of MTV India in south Mumbai seem to embody the fusion of local and international culture on which MTV prides itself. Huge posters of American pop stars such as Britney Spears and Prince jostle for space alongside cardboard cut-outs of Bollywood film stars. Hindi music plays loudly and there is even a statue of the Hindu god Ganesh. But is everything as harmonious as it seems?

I came to Mumbai to investigate the impact of MTV around the world for the BBC World Service. MTV India is one of the most successful global channels, and I wanted to find out whether it reflects the growing confidence of a changing India, or the country's Americanisation.

When MTV launched in India in 1996, five years after economic liberalisation, it transmitted the usual western brand of pop and lifestyle shows. The channel was a flop. It was forced to "Indianise", and relaunched in 1997 with Indian presenters and a high proportion of Hindi music. Ashish Patil, who oversees creative content, argues that his network has embraced Indian tastes such as Bollywood music. He says it has played a crucial part in "making desi cool" - by desi he means Indian identity. "People are proud to be Indian," he says. "It's no longer about a T-shirt that says 'I love New York'. It's about a T-shirt that says 'I love Cochin', or 'I love Kerala'."

This view is not without its critics. "It's like putting a potato patti in a hamburger and saying it's 'desified' the hamburger," says the novelist and journalist Shobha De. "It's about as real, tasty and appetising as that." Niti Sampat, a professor of media in the English department of St Xavier's College, Mumbai, agrees. "The way we look at ourselves in India is very derivative, and this is reflected by MTV. It is an American presenting style we have appropriated. Maybe we dress a little differently, and we use Hinglish [a mixture of English and Hindi] to make it seem like it's not American - but that doesn't change the fact that it's derived."

Saris, wigs and contact lenses

In India MTV presenters, known as VJs, are heroes. When I meet Cyrus Broacha and Cyrus Sahukar, they are dressed in saris and wigs to record a spoof comedy show. They argue that they have added their own brand of humour and they pride themselves on their use of Hinglish. Cyrus B says words such as "enjoy" take on a new meaning; in this case, a sense of love or fun. But Cyrus S is more cautionary. "Everything has happened so quickly. We have this explosion of hundreds of channels," he says. "Today when I go into a club I see people wearing green and magenta contact lenses like they're in a horror show. In a sense it would be better if things moved more slowly."

But how far is MTV accountable for these cultural changes? The rapid appropriation of western ways is part of a bigger process of economic growth and globalisation. On my last night in Mumbai, I meet Roshnee, a young journalist, at a trendy bar where U2 plays in the background. She was part of the original MTV Generation, and yet is highly critical of its influence. "MTV has given airtime to all the multinationals, so now corner shops which used to sell dhal sell skin-whitening creams," she says. "We are all brown, but even though you know that is the natural colour of your skin you try to get rid of it. India is about a herd mentality. We are mimicking because we are trying to find ourselves through MTV, rather than just trying to find ourselves."

"Close Up: the MTV generation" goes out on the BBC World Service on 21 July and 28 July at 9.30am, 3.30pm, 7.30pm and 11.30pm