India's autonomous election commission has ordered an inquiry into complaints of widespread vote-rigging and other irregularities in the Chhapra parliamentary constituency in Bihar.
The party that heads the federal governing coalition - the Bharatiya Janata Party (BJP) - has been demanding a re-poll in the constituency.
It says voting there last Monday was neither free nor fair.
The BJP fielded a federal minister, Rajiv Pratap Rudy, as its candidate in Chhapra.
His opponent is Laloo Prasad Yadav, a former chief minister of Bihar, and the leader of the party that governs the state.
The election commission said a two-member team would soon visit Chhapra for a detailed inquiry.
From the newsroom of the BBC World Service