The fast is led by Team Anna member Arvind Kejriwal while Anna Hazare, the septuagenarian social activist who fired the country's imagination a year ago on an anti-corruption plank, said he would join the hunger strike from July 29 if the government failed to take immediate steps to check corruption in high places.

Hazare, along with Kejriwal and two other members Manish Sisodia and Gopal Rai, paid tributes to Mahatma Gandhi at Rajghat before beginning the protest. Team Anna has got permission to fast at Jantar Mantar till Aug 8, the day parliament's monsoon session is expected to begin.

"We are demanding a strict Lokpal bill but this government has betrayed us several times," Hazare told reporters before the protest began in the heart of the capital.

The Team Anna show attracted around 2,000 people, but the enthusiasm and fever of the anti-corruption crusade of last year was missing.

This did not dampen the spirits of the activists who aggressively raised the pitch for ridding India of corruption and targeted some of the most powerful in the country.

They did not even spare Mukherjee, who was sworn-in as the country's 13th president in the morning, for his alleged role in corruption during his tenure as defence and finance minister.

Hundreds of people, including schoolchildren and retired government officials, assembled at Jantar Mantar to pledge their support for Hazare and his cause.

Mukherjee was one of the 15 cabinet ministers named by the Team Anna for being involved in corruption.

The podium had pictures of all the tainted cabinet ministers while a cloth covered Mukherjee's image.

"We have given evidence against Mukherjee to Manmohan Singh but no action was taken. Being the president, he now has immunity against any investigation, so we have covered his face," said Kejriwal.

Kejriwal reiterated charges that the prime minister was directly responsible for giving away coal blocks to unknown companies at throwaway prices between 2006 and 2009 when he headed the coal ministry.

Team Anna also attacked Home Minister P. Chidambram, Human Resource Development minister Kapil Sibal and Congress leader Virbhadra Singh for their alleged complicity in corrupt deals.

A ruckus ensued at Jantar Mantar when some youths, claiming to be from Congress students wing, tried to take the podium shouting slogans against the activists.

The youths claimed to belong to the National Students Union of India (NSUI). But the NSUI denied any link with the incident.

"Some members of NSUI tried to enter the stage where Anna Hazare was sitting but were stopped by volunteers," a member of Team Anna told IANS.

The Congress accused Team Anna of trying to create a controversy by blaming NSUI.

"It is an unfounded allegation not based on facts. They are trying to create a controversy by naming the NSUI," said Minister of State in Prime Minister's Office V. Narayanasamy.

India against Corruption, which is pearheading the campaign, said its activists were not allowed to hold peaceful protests and were detained in many parts of the country including Kolkata, Pune and Mumbai.