The Centre on Thursday said that it has recommended a preliminary enquiry by the Central Bureau of Investigation into the purchase of 1,000 air-conditioned low-floor buses by the Delhi government, the Hindustan Times reported.

A preliminary enquiry is intended to ascertain whether a prima facie case for investigation is made out. It can be converted into a first information report when the agency has sufficient material to show that a cognisable offence has been committed.

The Delhi Transport Corporation floated a tender to purchase 1,000 buses in January. Chief Minister Arvind Kejriwal had said at that time that the buses would be on roads by September. The Delhi government’s procurement contract for the buses was valued at Rs 850 crore. It had also floated an annual maintenance contract worth Rs 3,412 crore for 12 years.

Delhi last inducted new buses into its fleet in October 2011.

However, in March, the Bharatiya Janata Party alleged in the Delhi Assembly that there was corruption in the annual maintenance contract to procure the buses. BJP MLA from Rohini, Vijender Gupta, had claimed there were irregularities in the purchase, according to PTI.

Lieutenant Governor Anil Baijal then formed a three-member panel to investigate these discrepancies in June. Some reports in July said that this panel had cleared the Delhi government of corruption charges and only found procedural lapses.

“The tendering process of purchase of buses warrants no interference and suffers from no major infirmity,” the report had said, according to the Hindustan Times. “The committee, prima facie, did not come across any material to impute criminal misconduct attributable to any public official. There were only procedural lapses apparently arising out of a bona fide decision-making process.”

It added: “However, a greater effort for understanding the market and a higher degree of due diligence in assessing reasonableness of bids was required compared to what seems to have been demonstrated.”

Baijal had referred the report to the central government in July. After examining this report, the Ministry of Home Affairs recommended a preliminary enquiry by CBI.

On Thursday, the Aam Aadmi Party government denied allegations of any irregularities. “It is a politically motivated conspiracy against AAP,” the government said. “The BJP wants to prevent the people of Delhi from getting new buses.

“In the past as well, the Centre has tried to harass the Delhi government using the CBI, but not even once has their attempt been successful because there has never been any truth to any of their allegations,” the AAP government added.

“The Delhi government does not believe in the politics of slander, it only believes in good governance and is committed to delivering upon its promise of good governance,” it said.