Opposition parties widely condemned Mr Kejriwal's arrest, accusing Mr Modi's government of misusing federal agencies to harass and weaken his political opponents, and pointed to several raids, arrests and corruption investigations of key opposition figures in the months before the national election.
Modi's party seeks to topple Delhi leader as India's capital goes to polls State election is a largely direct fight between BJP and incumbent Aam Aadmi Party.
The election was seen as a test for Mr Modi and his BJP, which lost its majority in last year’s national election and was forced to form a coalition government.
Mr Modi's party hoped to benefit in Delhi after last week's federal budget slashed income taxes for the salaried class, one of its key voting blocs.
Mr Kejriwal, an anti-corruption activist, formed the AAP in 2012 after tapping into public anger against the Congress party’s then federal government over a series of corruption scandals.
