NEW DELHI (AFP) - India's Prime Minister Manmohan Singh declared on Tuesday his embattled government has "nothing to hide" and was "making all efforts" to find missing files sought for a high-profile corruption probe.

Singh told parliament more than 150,000 documents have already been handed over to investigators probing the allocation of coal mining licences, bowing to opposition demands to make a statement over the scandal.

"The government has nothing to hide," Singh told parliament.

"Some members have gone ahead and drawn their own conclusion that there is something fishy and the government is hiding something."

"The fact that more than 150,000 pages of documentation have already been handed over to the Central Bureau of Investigation (CBI) clearly shows that our intention to facilitate the process of investigation cannot be called into question," he said.

The CBI has been probing allegations by the national auditor last year that the government, when granting coal mining rights, may have given away billions of dollars in windfall gains to 100 private and some state-run firms in exchange for kickbacks.

Coal Minister Sriprakash Jaiswal admitted in July that some files from 1993 to 2004 were missing and that a panel headed by a senior ministry official was probing the matter.

The main opposition party called for Singh to step down when the scandal erupted, saying the government bore responsibility for the vanished files.

Singh said his government would comply with a court ruling to provide within two weeks all documents requested by the CBI.

"The government... shall do its best to locate and hand over the requisite papers to the CBI within the time frame," Singh said.

"If records in question are indeed missing, the government will carry out a thorough investigation and ensure that the guilty are brought to book."

Singh's coalition government, dominated by the left-leaning Congress party, has been beset by a string of corruption cases in recent years.

The latest allegations of mismanagement have piled pressure on him ahead of elections due by next year.