New Delhi: Stung by the Vyapam scam, Bharatiya Janata Party (BJP) on Thursday mounted its offensive against Congress by accusing Himachal CM Virbhadra Singh of taking bribe from an energy firm for giving it a 10-month extension and buying a farm house in Mehrauli.

BJP, which had yesterday released a sting video accusing Uttarakhand Chief Minister Harish Rawat of corruption, followed it up today by training its guns on Singh, saying it would continue with its "instalments" against the opposition party leaders.

The charges raked up by the BJP today were first levelled against Singh during the Himachal Pradesh Assembly elections in 2012 and the party leaders today quoted from probe document to claim that the charges against him stand "proved" and demanded his resignation.

Addressing a press conference here, union minister Ravi Shankar Prasad alleged that Virbhadra Singh was involved in tax evasion.

“We demand the Congress’s answer on this. The BJP is asking a clear question: (Congress vice-president) Rahul Gandhi please explain why and how is it that your powerful CM (Virbhadra Singh) is giving an extension to a cancelled project of Venture Energy & Technology Private Limited?” Prasad said.

He was referring to a private company that allegedly transferred Rs 1.2 crore into Singh’s bank account in 2013 to approve an extension to its hydel project in Chamba district.

"Rahul Gandhi ji, Sonia Gandhi ji please explain... Is it quid pro quo or not? It is clear case of bribery... Will you ask Singh to resign?" Prasad joined by party spokesperson MJ Akbar and Himachal in-charge Shrikant Sharma said.

HImachal CM's son Vikramaditya Singh and daughter Aparajita purchased the property in Mehrauli through their company Maple Destination and Dream Build Pvt Ltd for Rs 6.61 crore.

However, refuting the charges, Singh later in a tweet said that the BJP was raising "old and unsubstantiated charges" against him and accused the Centre of "political witch-hunting".

I strongly deny the allegations made by @rsprasad & @BJP4India is diverting public attention frm burning issues which it is deeply embroiled — Virbhadra Singh (@virbhadrasingh) July 23, 2015

Everybody is aware about false & fabricated cases filed against me by @BJP4India govt & every time I came out clean from the Hon’ble Courts — Virbhadra Singh (@virbhadrasingh) July 23, 2015

"The BJP is desperately trying to divert the attention of media and people from the questionable conduct of their leaders for which they have no answer," the veteran Congress leader said.

Speaking to news agency ANI, Virbhadra Singh said he is ready to face a second CBI probe into the allegations made by BJP. “Made-up charges by the BJP can't tarnish my image,” Singh added.

He further said, "BJP just want to attack me because certain BJP CMs have been exposed,they are trying to hide their own shame by blaming others."

"I don't want to go into details as the matter is sub judice in SC, Delhi HC and Himachal HC," he added.

While rejecting the bribe charges leveled by BJP, Singh said, "I totally deny it, everybody knows about my reputation, honesty & integrity, this is mud-slinging on part of BJP."

"I'm totally innocent, an attempt is being made to frame me up, and I know truth prevails in the end," he added.

BJP had yesterday released a sting video concerning Uttarakhand Chief Minister Harish Rawat and demanded his resignation over "liquor scam" worth hundreds of crores and "loot" carried out during the 2013 floods.

The Congress, however, said the Uttarkhand government had acted swiftly following the allegations and an FIR was being registered.

With CBI initiating a preliminary enquiry against Virbhadra Singh's assets case, BJP, last month, demanded his immediate resignation to allow a probe to take place independently and demanded a public apology from Congress president Sonia Gandhi and vice president Rahul Gandhi for allowing scams.

BJP also accused Congress of promoting corruption and charged the party's top leadership with allowing corrupt leaders to flourish during its regime while rejecting charges of "vendatta politics" levelled by the opposition party.

(With Agency inputs)