New Delhi, May 16 (IANS) : The Bharatiya Janata Party (BJP) Saturday conceded defeat in the Lok Sabha elections and congratulated Prime Minister Manmohan Singh and UPA chairperson Sonia Gandhi for their victory even as it top leader L.K. Advani offered to step down as leader of opposition.

As the results made it clear that the Congress-led United Progressive Alliance was winning the Lok Sabha polls, BJP's prime ministerial candidate Advani expressed his wish at a meeting of the BJP parliamentary board to step down as leader of opposition in the Lok Sabha.    

"He made his wish known that a new leader should be elected (in his place). The party parliamentary board rejected his suggestion," BJP general secretary Arun Jaitley told a press briefing, adding that the veteran leader however was insistent.   

"BJP national president (Rajnath Singh) will talk to him further on this topic and take further decision on this later," he said.   

Jaitley added that Advani will continue to be involved with the party. "He will continue to guide the party. The party will in fact like him to continue, which is a desire which we all expressed," he said.   

The meeting was attended by Rajnath Singh, Jaswant Singh, M. Venkaiah Naidu, Sushma Swaraj and Jaitley among others.   

Jaitley said that no BJP member has offered their resignation after the poor showing of the party - "and none are expected".    

"It is a collective responsibility of the whole party," he said, adding that the verdict will be discussed internally at various party forums.   

The BJP formally conceded defeat after the meeting of the parliamentary board meeting, stating that the UPA should be asked to form the government and that it will play the role of "constructive opposition".   

"Even though no party or alliance has got a clear majority, BJP believes that the best mandate to rule is in favour of UPA. The BJP believes that the logical culmination is that the UPA being invited to form the UPA," he said.   

Jaitley said Advani had called up Prime Minister Manmohan Singh and Congress president Sonia Gandhi to congratulate them on their victory. "He has assured them of full cooperation on behalf of BJP," he said.   

He said the BJP and its allies while "acting as constructive opposition will fully cooperate with the government".   

The BJP-led NDA has won or is leading in 164 seats, as opposed to the UPA's 258.   

Admitting that the party had not "fared as well as expected", Jaitley said: "BJP accepts the mandate of people of India with full humility. We shall do our utmost to honour the spirit of this mandate".   

Reading out a statement, Jaitley said: "India needs political stability. It needs to put the national economy on track. It needs to strengthen national security. For these challenges people have given a mandate to the UPA leadership to govern. The BJP and its allies while acting as a constructive opposition will fully cooperate with the government in strengthening India."    

He said the party will now analyse the results. "We did well in several states while in some states our performance is below our expectations."   

He said a more detailed analysis will be done later, but added that the UPA victory was more due to the rejection of 'Third front politics' than any rejection of NDA.   

"The NDA has done reasonably well in several states, so you can't say it's rejection of NDA politics... The kind of politics that the Third Front was throwing up has a far greater rejection rather than the marginal dilution of some of our seats in four-five states."   

Jaitley admitted the party performance was far below expectations as they did not manage the number of seats that they won in 2004. However, he added that the NDA managed to touch 107 seats, despite some allies like Biju Janata Dal (BJD) breaking off.   

Asked if the verdict was in favour of national parties or regional ones, he said: "Obviously, national parties have done well. But, then look at Orissa, Bihar, where the regional parties have done very well."