Uttar Pradesh Chief Minister Mayawati on Friday approached the Supreme Court seeking to quash CBI investigations against her in a disproportionate case registered five years ago.

She alleged that the investigating agency was used by the Centre to secure political ends and probe against her was aimed at "character assassination".

The petition was mentioned before a Bench headed by Chief Justice K G Balakrishan for early hearing.

However, it said the matter will be heard in routine course on May 15.

The CBI had registered FIR against Mayawati on October 5, 2003, allegedly on the direction of the apex court, which had ordered the agency to investigate Taj Heritage Corridor Scam.

The Bahujan Samaj Party chief contended that the FIR lodged against her was illegal as no sanction was taken from the state and the agency had misinterpreted the apex court order, which only directed investigation into the Taj Corridor case.

"Lodging the FIR and investigating into her assets is beyond the purview of Taj Heritage Corridor case and is a direct onslaught on her fundamental rights," she said in her petition adding, "keeping the sword of investigation hanging has seriously impaired her political journey."

"The premier investigation agency has unfortunately been used as a tool by the Central government by lodging the illegal FIR so as to harass her and proceeding of which are creating obstruction in smooth running of the government in the state," she said.

Mayawati said though her party supports the United Progressive Alliance government at the Centre, differences between them was a matter of public knowledge and the investigating agency was being used to secure political ends by abuse of the legal system.

Under these circumstance "the need for effective enforcement of checks and safeguards to permit the state chief minister to function freely and fearlessly without concern of undue interference by the Central government becomes more pronounced," the petition said.

"The present case is a text book example of the overreach by a agency under control of the Union government, giving rise to reasonable apprehension of an attempt to create a lever to try to secure political ends by an abuse of legal system," she alleged.

"The present ongoing investigation against the petitioner (Mayawati) is nothing but her character assassination and therefore, smacks of malafides on the part of CBI," the petition said.