Lucknow, Mar 9 : The formal alliance between the Congress and Samajwadi Party may have fizzled out but there would be a 'tacit' understanding between the two in the coming Lok Sabha polls in Uttar Pradesh.

An informal agreement in this regard has been reached between the two parties as they were of the common view that the corrupt BSP and the communal BJP should be stopped from reaching the Centre, highly placed Congress sources told UNI here today.

''There is no heart burn between the two parties even as the alliance failed and we have decided to contest under a strategy to defeat the BSP and BJP candidates in the fray,'' sources said.

The SP, which has already announced 71 out of a total of 80 candidates from the state, had put the candidates in such a way that the BSP and BJP did not get any lead in the polls, a top UP Congress leader said.

''Congress will support strong SP candidates in any constitunecy by fielding a comparatively weak candidate and vice-versa,'' he said.

Citing example of Bareilly Lok sabha seat, the Congress leader pointed out that the candidature of SP's Bhagwat Sharan Gangwar was clearly aimed at defeating rather strong BJP candidate Santosh Gangwar and strengthening Congress candidate Pravin Singh Airon.

Admitting that the Kalyan Singh factor was the main stumbling block in the alliance negotiations, the Congress sources said ''declaration of Mr Kalayan Singh's support without taking the Congress into confidence was a no-no from us.'' The Congress has always expressed its reservation over former BJP leader and Ayodhya mascot Kalyan Singh's support to the SP. The Congress general secretary and incharge of UP affairs Digvijay Singh was candid in his observations that even in case of an alliance with SP, the Congress would never share dias with Mr Singh, who is guilty of the Babri demolition on December 6, 1992.