A day after forging alliance with Janata Dal (United) and Apna Dal for Uttar Pradesh assembly elections, the Bharatiya Janata Party on Monday said it will ask its alliance partners not to field any candidate with criminal or tainted background.

"Though choosing a candidate will remain their prerogative, we would request them to keep criminal elements out," senior BJP leader Kalyan Singh said, adding, "the BJP has decided it will not field any candidate with criminal background."

Taking strong exception to a report in a section of media suggesting Singh wanted to field candidates with criminal background, Singh said it was a 'highly serious' matter and will request the party's national president to probe into the persons behind the 'disinformation.'

"It is an attempt to defame the party ahead of polls," Singh said, declining to take any specific name or the party.

Asked if the alliance will need to seek the support of Mulayam Singh's Samajwadi Party to maintain a clear majority, Singh said, "We would have no truck with the SP for its nexus with criminals and mafia. I would rather sit in Opposition than come to power with the support of criminal elements."

The alliance, formed on Sunday to take on the SP and Bahujan Samaj Party in the state assembly elections, has chosen Singh as their leader. Singh also said the distribution of seats to be contested by alliance partners would be finalised shortly.

Law and order, spiralling prices, farmer suicides, power crisis and unemployment will top the election agenda of the alliance.