Divestment process of state-run refiner Hindustan Petroleum Corporation Ltd is gaining momentum with the divestment ministry readying the data room for starting the due diligence process.

"It takes time to prepare these data room that is getting prepared," Divestment Minister Arun Shourie told reporters in New Delhi on the sidelines of a stamp release function.    

Shourie said the process of divesting the government's 34 per cent stake in India's second largest oil refining and marketing firm had begun in right earnest but did not specify any timeframe for privatisation.

Over half a dozen firms including Royal/Dutch Shell, Petronas of Malaysia, Kuwait Petroleum Corporation, Saudi Aramco, Reliance Industries and Essar Oil are in the race for picking government stake in HPCL.

Divestment minister also did not give any timeframe for beginning the due diligence process.

On the divestment of government stake in Bharat Petroleum Corporation Ltd, Shourie said, "advisors will (soon) begin their work."

Valuation of BPCL would be done before a prospectus of the public offering is prepared. "That takes time," he said.

Last week, the government appointed DSP Merril Lynch as its global advisor for the public offering of its stake in BPCL.