New Delhi — An anti-corruption activist arrested Tuesday for planning a public hunger strike began his fast behind bars as his supporters held protests across the country, with thousands detained by police.

Anna Hazare’s demand for tougher anti-corruption laws has tested the beleaguered government and galvanized Indians fed up with seemingly endless scandals exposing bribery and favoritism and paralyzing efforts to address poverty and speed development.

Hazare, a 73-year-old social activist clad in the simple white cotton garb of India’s liberation leaders, has become an anti-corruption icon by channeling the tactics of freedom fighter Mohandas K. Gandhi.

In April, he used a four-day fast to force the government to draft legislation to create an anti-corruption watchdog. He had planned to begin another public fast Tuesday to press for a stronger bill.

Police barred his latest protest after organizers refused to limit the number of fasting days and participants, Home Minister Palaniappan Chidambaram said. “Protests are perfectly permissible and welcome, but it must be under reasonable conditions,” he said.

Hazare vowed to carry on regardless, but was arrested before leaving for the protest site in a New Delhi park.

He waved cheerfully at news cameras outside his home as he was driven away to a police mess hall, where he began his fast. Later, after refusing to post bail, Hazare was taken to New Delhi’s Tihar jail for seven days of detention, joining business leaders and three lawmakers who are facing corruption charges there.

His supporters released a video appeal Hazare had recorded anticipating his arrest.

“My dear countrymen, the second freedom struggle has begun, and now I have also been arrested. But will this movement be stopped by my arrest? No, not at all. Don’t let it happen,” he said.

Thousands rallied across the country, carrying placards calling for a “Revolution Against Corruption” and taunting authorities to “Please Arrest Me.” They decried Hazare’s arrest as an antidemocratic affront to civil rights. Some donned white caps resembling Hazare’s with the words “I am Anna Hazare” scrawled in Hindi or English.

Police rounded up at least 1,200 protesters in New Delhi and more than 3,000 in Mumbai, but many were later released. Across Maharashtra state, where Hazare’s village of Ralegan Siddhi is located, hundreds of people temporarily blocked roads in protest.

Hazare’s supporters later urged government workers to show solidarity by going on strike Wednesday. The home minister said he hoped workers “will not respond to such a wrong call.”

Chidambaram said the government was only seeking to maintain order in arresting Hazare.

“We are not prohibiting a peaceful democratic protest,” he said, noting that Hazare’s camp had rejected police conditions for holding a safe rally. “Nowhere in the world is a protest allowed without any conditions.”

The governing Congress party went further in its defense, accusing Hazare of meddling in politics and hijacking public policy with his fast when he should instead express his views to elected officials.

“He is not fighting against corruption but doing politics,” party secretary-general Digvijay Singh said, noting the government’s right to take steps to avoid a situation that threatens law and order.

The hunger strikes have catapulted the issue of India’s culture of graft to the top of TV news and inspired others across the nation to fast in solidarity, as the gulf between India’s rich and poor, the vast majority of its 1.2 billion people, has widened despite two decades of economic growth.

The government is battling corruption allegations stemming from the murky sale of cellphone licenses and the hosting of last year’s Commonwealth Games, which together lost the country as much as $40 billion, according to government auditors. The main opposition is mired in a multibillion-dollar bribery scandal involving the granting of mining contracts in southern India.

The scandals have embarrassed the government and paralyzed Parliament, with lawmakers trading insults and accusations instead of addressing widespread malnutrition and a desperate need for land reform. On Tuesday, Parliament adjourned amid screaming between government and opposition lawmakers over Hazare’s arrest.

The main opposition party slammed Hazare’s arrest as evidence that the government is “imbalanced” on the issue of corruption, and demanded Prime Minister Manmohan Singh himself address the controversy.

“The government is hell-bent on crushing civil rights of the citizens,” said Sushma Swaraj, leader of the nationalist Bharatiya Janata Party.

Singh addressed the issue in his annual independence day speech Monday, saying his government was committed to taking the “strictest possible” action against corrupt officials but that only Parliament can decide anti-corruption legislation.

He said those who disagree with the proposed legislation should debate it and “not resort to hunger strikes and fasts unto death.”