The Bharatiya Janata Party on Tuesday fired yet another salvo at the UPA government on the Indo-US nuclear deal, saying the difficulties faced by it in operationalising the agreement reflected the very nature of the 'opportunistic alliance.'

A day after Prime Minister Manmohan Singh [Images] told President Goerge W Bush about hurdles in implementing the deal, Leader of the Opposition L K Advani insisted that the nuclear pact standoff was 'the lowest point of the UPA government.'

"It is a reflection of the nature of this alliance, which has parties with diametrically opposite views on foreign and economic policies. It is bound to happen in an opportunistic alliance," Advani told PTI in New Delhi.

He was replying to a question on the prime minister's late night telephonic talk with Bush during which Dr Singh talked about difficulties being faced by his government in proceeding with the deal.

Advani said the deal with the US was 'uncalled for and undesirable' as it surrenders India's strategic freedom by bringing the country into the nuclear non-proliferation regime.

"No government of the past ever agreed to it. Indira Gandhi [Images] had rejected it. The Vajpayee government conducted Pokhran II (nuclear tests) despite displeasure from the US government," he noted.

The veteran BJP leader asserted that the BJP will 'renegotiate' the deal with the Indian national interest in mind if it comes to power.