AAP workers protest in at BJP headquarters in Delhi on Wednesday, March 3.

The police used batons and water-cannons at the BJP's headquarters in the heart of Delhi after a riot erupted there when workers of Arvind Kejriwal's Aam Aadmi Party gathered there to protest their leader's brief detention by the Gujarat police this afternoon. ( Gujarat police detains Kejriwal briefly provoking angry charges Senior members of the Aam Aadmi Party or AAP alleged that stones and chairs were hurled at them from within the BJP office. The BJP's Nalin Kohli said that was in self-defence. "These are urban Maoists," said the BJP's Prakash Javadekar. ( See pics This afternoon, Mr Kejriwal was detained briefly by the police in Gujarat in the western town of Radhanpur. Mr Kejriwal says the police's action was ordered by Narendra Modi , who is the BJP's candidate for prime minister. ( Read more Mr Kejriwal is on a four-day tour of Gujarat where he says he will conduct on-the-ground checks of the extensive development of the state that has been highlighted by Mr Modi and the BJP in its election campaign.Mr Kejriwal was detained for failing to adhere to an election code of conduct that requires prior police permission for rallies or processions. The code of conduct has kicked in today because elections have been called starting April 7. Results will be declared on May 16. ( See India's voting schedule "He was not there to hold any election rally. He had only gone there to watch and observe the development that Modi is claiming has taken place in the state," countered Kumar Vishwas, a senior leader from the Aam Aadmi Party.Opinion polls favour Mr Modi and the BJP to emerge as the largest party, but say it will fall well short of a majority. ( India's mammoth general election: factbox





Mr Kejriwal, whose stunning breakthrough in the Delhi state elections in December highlighted public anger towards the political establishment, is taking on the major parties at the election.