Rejecting Uttar Pradesh Chief Minister Mulayam Singh Yadav's charge that the phones of Samajwadi Party leaders, including Amar Singh, were tapped, the Union Home Ministry on Friday conducted an immediate in-house probe and registered a case of criminal conspiracy and forgery against 'unknown persons'.

Shortly after Yadav made the charges against Congress President Sonia Gandhi [Images], Joint Secretary (Internal Security) in the Union Home Ministry L C Goyal said the allegations were baseless.

He said no phone was being tapped either at the instruction of Delhi Police or the home ministry.

"The matter has been examined by the Delhi police commissioner and principal secretary (home).

"The documents and the evidence available with them and the telecom service provider, cited as the basis of such monitoring, appears to be a clear case of forgery," he said.

A case under various sections of Indian Penal Code dealing with forgery, cheating and criminal conspiracy and relevant laws under Indian Telegraph Act was registered, Patil said.

Yadav had alleged in Lucknow earlier in the day that the government was tapping party General Secretary Amar Singh's phone, for which Reliance [Get Quote] Infocomm is the service provider.

Sources in the ministry said the officials of the telecom service provider will also be questioned.