Overcoming health problems, former Prime Minister Atal Bihari Vajpayee opened his campaign for the Uttar Pradesh assembly polls in Lucknow on Wednesday night.

He launched a veiled attack on the Mulayam Singh Yadav government for hurdles in the development of the state.

Addressing a well-attended rally, Vajpayee said the Bharatiya Janata Party's return to power in the state was necessary for its prosperity.

Vajpayee said the support BJP was receiving in the polls was a good indication but counselled party workers to maintain unity in their ranks, which was essential for electoral success.

The BJP could defeat its rivals in Punjab and Uttarakhand Assembly only because of its unity. Reminding the people of May 11 next, the day Pokharan II nuclear test was conducted in 1998 by his government, Vajpayee said the counting of votes for the UP Assembly polls would also take place on that day, which could again be a historic day as it could bring BJP back to power in the state.

Vajpayee referred to increasing pollution in Gomti River here and said something must be done in this regard and also assured his full cooperation.

This was the first election meeting Vajpayee addressed in the state during the on-going seven-phase elections.

BJP President Rajnath Singh referred to the ongoing CBI probes against UP Chief Minister Mlayam Singh Yadav and BSP chief Mayawati and alleged these two leaders had created a crisis of political credibility in the state.

Singh said the CBI should complete the probe into the disproportionate assets case against Yadav and corruption charges against Mayawati at the earliest.