NEW DELHI An anti-corruption movement led by the feisty 74-year-old social activist Anna Hazare is snowballing into one of the biggest challenges in decades for the ruling Congress party and if not contained risks sparking India's own version of an Arab Spring revolt.
While no one is expecting an Egypt-like overthrow in the world's biggest democracy, a galvanised and frustrated middle class and the mushrooming of social networking sites combined with an aggressive private media may be transforming India's political landscape.
Hazare has quickly become a 21st century Mahatma Gandhi inspiration for millions of Indians fed up with rampant corruption, red tape and inadequate services provided by the state despite the country posting near-double digit economic growth for almost a decade.
"Democracy means no voice, however small, must go unheard. The anti-corruption sentiment is not a whisper-it's a scream. Grave error to ignore it," Anand Mahindra, one of India's leading businessmen and managing director of conglomerate Mahindra Group, wrote on Twitter.
Hazare's arrest on Tuesday, only hours ahead of a planned fast until death against graft was the last straw and sparked spontaneous protest across the country of 1.2 billion people.
The young and old, rich and poor, without apparent political affiliations, took to the streets in a rare voice of solidarity -- a potential lethal cocktail for any party in power in India.
Politicians are increasingly being judged on governance rather than old caste and regional ties - as has already happened in states like Bihar - and the new social shift will push national parties to be more responsive to voters' needs.
Prime Minister Manmohan Singh, the Congress party of the Gandhi-Nehru dynasty and the police stood isolated over the decision to arrest a man for planning a peaceful fast.
The Congress has for the past year reeled from mounting corruption scandals, including allegations of millions of dollars in kickbacks in the sale of mobile phone licences in what is emerging as India's biggest-ever graft.
Former telecoms minister Andimuthu Raja, top corporate executives and senior Congress party officials are in jail awaiting trial.
Indians have routinely voted out governments and in that sense the anti-graft movement is different from those sweeping the Middle East.
The next election is due in 2014 and an opinion poll last week by India Today showed that if elections were held today, Congress would just about lose out to the main opposition party.
In a passionate speech in parliament, 58-year-old Bharatiya Janata Party (BJP) leader Arun Jaitley said protests witnessed over the past 24 hours, reaching even the remotest villages, were something he had not seen in his lifetime and must be a "wake-up call" for politicians to put their house in order.
Students, lawyers, teachers, and business executives have taken to social networks like Twitter and Facebook to spread the message and vent frustration against corruption.
"These protests are part of a global phenomenon, thanks to technology and a more proactive media," said N. Bhaskara Rao, social researcher and chairman of independent think-tank Centre for Media Studies.
Most people do not expect India to follow the example of North Africa and the Middle East. But one of five Indians go hungry and almost half the vast population is poor -- causes for potential unrest.
India has been governed for most of the time since Independence in 1947 by the same family dynasty. For decades Indians united under these leaders but this year has seen a seismic gap emerging between the old guard and a vibrant and younger population.
"This has the ingredients of being India's own non-violent Arab uprising," said Savio Shetty, a stock market analyst in India's financial hub Mumbai.
"But the dish needs to be cooked and looked after! Tahrir square was a rebellion against the government itself ... of a 40-year tyrannical rule ... things are quite different here."
Singh remained defiant in parliament over the arrest of Hazare, maintaining that anti-graft laws should be discussed and passed in parliament and not by activists in the streets.
"When people exhaust their capacity for tolerance, then you should take it that it is a beginning of some kind of revolution. Now it has gone above people's tolerance level," Hazare told Reuters in a recent interview in his home village.
India ranked 87 in Transparency International's index on corruption in 2010, behind rival China and polls show corruption vies with the high cost of living as the number one voter issue.
What is also apparent is that the anti-corruption protests have shown the limited influence of opposition parties, largely sidelined. They will need to reform to win over an increasingly disenfranchised population.
NEW POWER -- MIDDLE CLASS
The bulk of India's political activism has been those aligned to political parties or paid to protest on their behalf.
But in recent years a growing and more prosperous middle class has given up its traditional distaste for politics and is seeking ways to exert greater influence.
"The new corporate middle class has little patience with the politics of dignity and identity that are -- for better or worse -- central to Indian politics," wrote Vinay Sitapati in the Indian Express newspaper.
Almost half of India's 1.2 billion population are farmers, many live on government subsidies and are reluctant to challenge local and national governments over endemic graft.
But with costs of living rising fast and daily news reports of state officials with meagre salaries caught with bags of cash and kilogrammes of gold, or registered as owners of multi-million-dollar homes, patience seems to have been snapped.
"Now citizens want to play a more participatory role in governance," said Rao. "This will bring in a sea change in Indian politics."
(Additional reporting by Anurag Kotoky in New Delhi; Henry Foy and Divya Chowdhury in Mumbai; Editing by Alistair Scrutton and Sanjeev Miglani)