Suhail Hindustani, alleged to have acted as a liaison between Amar Singh and BJP MPs who were bribed during the 2008 trust vote, appeared on Wednesday before Delhi Police for questioning and alleged that the former SP leader was behind the operation to buy lawmakers.

Hindustani arrived at the crime branch office in Chanakyapuri this morning along with some supporters who garlanded him. He was carrying a bouquet which he claimed was for a senior police official quizzing him to express his "profound" gratitude to the force for going ahead with the probe.

Before entering the police complex, Hindustani told reporters that he would tell police whatever he had told the parliamentary committee which probed the infamous cash-for-vote scam.

Hindustani, who claimed that he was earlier a BJP youth wing Yuva Morcha member, alleged that the operation was done by Amar Singh and some Congress leaders. He said police should examine his call records, which he claimed would throw light on who all called him between July nine and 22 of 2008.

He alleged that Singh and some Congress leaders were in constant touch with him.

"I will tell all these things to the police. They had approached me to get MPs from the BJP to save the government.

They offered me posts like chairmanship (in some corporations)," he alleged.

Hindustani's appearance before investigators came as police issued a notice to him asking him to join the probe after arresting Sanjeev Saxena, once considered close to Singh, for allegedly delivering cash to three BJP MPs.

Expanding its probe, police has also initiated the process to possibly question Amar Singh and BJP MP Ashok Argal.

Police may also question Sudheendra Kulkarni, a former aide of L K Advani, in connection with the scam.

Developments in the case came after the supreme court rapped the Delhi Police for its "callous" approach in probing the case. The police had filed an FIR in 2008 after a Parliamentary panel recommended it to investigate the case.

BJP MPs had displayed wads of cash in lok sabha on July 22, 2008 alleging that their MPs Argal, Faggan Singh Kulaste and Mahavir Bhagora were given money by Saxena allegedly at the behest of Singh and others to vote in favour of the government.

The three MPs, who were approached allegedly by Saxena to vote in favour of UPA, had claimed that Saxena had told them that the money was given by Amar Singh.

During the questioning, police sources said, Saxena told investigators that he got the money from Singh but he was not sure whether the whole money came from the former SP leader.

Saxena also told police that he made a number of calls to Singh on July 21 and 22 of 2008 before and after the cash was delivered to the MPs.

Police is also looking for a driver, Sanjay, who took Saxena to the houses of the MPs and a mobile phone used by him to make calls while delivering the cash.

Investigators submitted that two out of three BJP MPs -- Kulaste and Bhagora -- have stated that on July 22, 2008, Saxena delivered money to them and Argal at the latter's residence here. Kulaste had earlier alleged that Saxena was introduced to him and Argal by Singh as his secretary.

The CBI is already probing Sachan murder case and opposition parties are also demanding CBI probe into alleged NRHM scam.