Former foreign minister Jaswant Singh has alleged that someone in the Prime Minister's Office during the P V Narasimha Rao-led Congress government had been leaking nuclear secrets to the US and 'we are still being snooped'.

The Leader of Opposition in the Rajya Sabha said he had come to know about it a decade ago but remained quiet so far as he did not want to sensationalise the issue.

"Yes, there was a person in the PMO. I have evidence, a letter which gives graphic details," Singh told India Today magazine, when asked to elaborate on his contention that there was a mole in the PMO of the previous Congress government.

Without naming anybody, the BJP leader claimed that 'somebody in the PMO was giving information about India's nuclear programme to the US. It was during the previous Congress regime'.

He said, "The honour of the Prime Minister's Office, to an extent, was at stake. We were snooped, we are still being snooped."

He said the letter (which mentions the PMO mole) came to him a decade back.

"I do not want to sensationalise it. I did not use it then. I did not use it when in government, I did not bring it up with the US government to tell them look here, this is what you were doing. All governments do try to find what is happening in which country. Diplomacy requires information," he said.

Singh is facing renewed attack over the 1999 Kandahar hijack crisis when he went with three terrorists to Afghanistan to exchange 161 passengers of Indian Airlines plane IC-814 held hostage.