The Indian government Tuesday stepped its up efforts to end national anti-corruption protests led by an activist's hunger strike, but the first meetings to broker a truce ended without result.

Top ministers from the ruling Congress party, under fire from the biggest social protests in decades, met aides of activist Anna Hazare in New Delhi in the late evening to try to end the impasse over implementing tougher anti-graft laws.

Prime Minister Manmohan Singh wrote a personal letter to Hazare asking him to end his hunger strike amid growing concerns over the self-styled, 74-year-old Gandhian activist's health, and called a meeting of political party leaders for Wednesday.

Hazare has lost nearly six kilograms since he began his fast to demand a bill to create an autonomous anti-corruption agency, a campaign that has drawn support mainly from the middle class against Singh's government.

The dialogue will continue and I am hopeful we will be able to work out a solution, said Finance Minister Pranab Mukherjee, one of the country's most experienced and powerful politicians, who was part of the talks.

Considerable progress made in talks with government, Kiran Bedi, a top Hazare aide, wrote on Twitter, though she told reporters Hazare would not stop fasting without a written commitment from the government to accept his demands.

Hazare's protest prompted the government to introduce the bill into parliament in August, though his supporters have slammed the existing draft as toothless.

Over the last few days, I have watched with increasing concern the state of your health, Singh wrote in his letter. At worst, our paths and methodologies may differ, though I do believe that even those differences have been exaggerated.

The bill is now parked with a parliamentary standing committee. The protesters want the government's draft bill withdrawn and their own version passed by the end of the month, a demand which senior government figures say is unrealistic.

But in another attempt at compromise, Singh also said in the letter that Hazare's version of the bill could also be discussed in parliament.

Speaking to supporters after the talks, Hazare's aides said the government was prepared to yield to a key demand to include the prime minister in the ombudsman's ambit, though sticking points remained on other issues. No government official confirmed the protesters' statements.

Hazare remained lying or sitting on a public stage on open ground in the capital for much of the day, surrounded by at least 10,000 supporters in the monsoon heat where open toilets and spilling waste were starting to cause outbreaks of food poisoning and illness.

His doctors have fretted about Hazare's worsening condition after the activist declined their advice to go to hospital or take medicine.

Who is scared of sacrificing their life? Hazare told his followers on Tuesday night, to loud cheers. I am not. That is what my conscience is telling me. 

With key state elections next year leading up to a 2014 general election, the government must end a crisis that has paralysed policy making and parliament and added to Singh's unpopularity amid high inflation and corruption scams.

Many of India's middle class, the fastest growing population segment, have joined forces with Hazare to protest a system that requires bribes for everything from driver's licences to birth certificates and a series of graft scandals that have touched top politicians and businessmen in Asia's third largest economy.

By mid-afternoon on Tuesday, thousands had gathered in the muddy, water-logged protest ground in Delhi. As a popular actor led songs and chants on a stage, a large number of students were walking in a procession, or passing by in trucks, shouting anti-government slogans.

People should continue with this struggle even if I'm not there, Hazare said. This is our second freedom struggle.

Hazare, who has carried out scores of hunger strikes over the last few decades to pressure governments, has been visited by Hindu gurus, former judges and Bollywood actors. But he has refused to have any politicians on his stage.

His deteriorating health could force the government to decide whether to force feed him -- a move that could spark further protests against a fumbling government of elderly ministers widely seen as out of touch.

A group of leftist and regional party members staged a sit in at parliament on Tuesday, one of two opposition protests against the government this week. The main Hindu nationalist opposition Bharatiya Janata Party is organising a nationwide protest against the government on Thursday.

Criticism of Hazare's hunger strike has also surfaced from activists and academics who say it is setting a bad precedent by holding democratic institutions hostage with his uncompromising stand. There have been criticisms from Muslim groups that he is too close to radical Hindu groups.

Hazare was briefly jailed last Tuesday, a move the government tried to reverse quietly. But he refused to leave prison until the government allowed him to continue his vigil, in public, for 15 days. He was released on Friday.

Several scandals, including a telecoms bribery scam that may have cost the government up to $39 billion, led to Hazare demanding anti-corruption measures.