The CBI, India's premier probe agency, is investigating how the coal ministry, which had been headed by Singh from 2004 to 2009, allocated mining licenses.

The Supreme Court is hearing the case.

The missing files and Singh’s potential role in the scandal have caused uproar in Parliament and disrupted proceedings.

Singh was silent on the issue until Tuesday when he made an identical statement in both houses.

“The fact that more than 150,000 pages of documentation have already been handed over to the CBI clearly shows that our intention to facilitate the process of investigation cannot be called into question,” Singh said, according to The Hindu.

“A vast majority of the papers sought by the CBI have already been handed over to them.

“However, disregarding the factual position, some members have gone ahead and drawn their own conclusions that there is something fishy and the government is hiding something.”

The “coalgate” scandal came to light last year when auditors alleged that the country lost $US33 billion from the government allocating coal blocks to private companies at below market rates.