"The Prime Minister now needs to display honesty and his good intentions towards fighting corruption and appoint the first Lokpal of the country," she said.
Her statement came hours after the apex court ruled that Lokpal and Lokayuktas Act, 2013, is a "workable piece of legislation" and it was not justifiable to keep its operation pending.
The Modi government has been misusing official machinery and hatching conspiracies in its bid to prove itself as honest and all others as dishonest and incorrect, she alleged.
She alleged that despite the law being enacted long back, it has been put on the back burner on one pretext or the other.
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"Narendra Modi government should now shun its stubborn attitude and ego and appoint Lokpal in compliance with Supreme Court orders without any delay," she said.
Modi had targeted Mayawati on the issue of corruption in the recent Uttar Pradesh Assembly elections. The BSP was trounced in the polls and won just 19 seats in the 403-member Assembly.
Last month, the government told the court that the Lokpal cannot be appointed for now as important changes to a committee that is to select its members have yet to be cleared by Parliament.
The changes involve redefining the "Leader of Opposition" post to enable the leader of the largest opposition group in the Lok Sabha to be a part of the Lokpal selection panel.
After the BJP came to power in 2014, the government said the leader of opposition's place in the Lokpal selection committee would stay vacant.
The government later made a concession and decided to include the largest opposition party in selection panels not just for the Lokpal but also for the CBI chief, the Information Commission and the Vigilance Commission.
The Congress has been cleared to participate in all but the Lokpal panel, whose other members are the Prime Minister, the Lok Sabha Speaker, the Chief Justice of India or a Supreme Court judge, and an eminent jurist.