The Bharatiya Janata Party on Saturday demanded that the probe into the oil-for-food scandal be handed over to the "highest investigating agency" that is empowered to conduct an inquiry at the international level.

BJP president Rajnath Singh, on the third day of his 'Bharat Suraksha Yatra', told reporters that the Pathak inquiry committee "lacked requisite authority" to conduct such a "wide-ranging" investigation.

Asked to identify the investigating agency, Singh said he was leaving it to the government.

He added that the government should take the NDA into confidence before deciding.

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He said the scandal had taken such a turn that the search for truth cannot be confined to mere departmental probe.

At the political level, he said, the Congress leadership must explain to the people its "role" in the oil-for-food programme.

The charge that a premier political party allowed foreign money to influence its stand on crucial foreign policy decisions "is too serious to be brushed aside", Singh said.

The Congress president, who headed the party during the time when the oil coupons were allegedly issued, owes an explanation to the country, he added.

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He said the ED investigations into the Indian links to the scam have taken a dramatic turn and that there are credible reports to indicate that the ED has unearthed at least two letters written by former eternal affairs minister Natwar Singh to former Iraqi foreign minister Tariq Aziz.

The BJP chief said the letter allegedly indicated that Natwar Singh introduced Andaleeb Sehgal, who has been named as a non-contractual beneficiary in the Volcker report, to Iraqi authorities.

Singh said these letters formed crucial links in the scam and suggested that Natwar Singh might not have been acting in his individual capacity but as a "representative" of the Congress party, which was also named as a non-contractual beneficiary.

The BJP leader said a similar charge of being influenced by foreign money was leveled last year in the Mitrokhin Archives based on documents in the possession of the British government.

At that time, he said, the BJP had pressed the Centre to put diplomatic pressure on the British government to release all the information pertaining to India.

"At a time when national security is under threat from various quarters, the country needs to know whether political decisions are taken on the strength of national interests or for collateral considerations," he added.