New Delhi : The Rajya Sabha on Wednesday witnessed acrimonious scenes during the zero hour over a sting operation in West Bengal as members from the Trinamool Congress and the Communist Party of India-Marxist exchanged heated words. While the Trinamool Congress questioned the authenticity of the video that allegedly showed Trinamool leaders accepting money for lobbying for a private firm, the CPI-M demanded a probe. Raising the issue in the Rajya Sabha during zero hour, TMC's Derek O'Brien said, "Let us not judge the credibility of the video; let's judge the source of the video." "Even the (TV news) channels are running the video with a disclaimer that they are not responsible for the content... In this age of technology, no one knows if it is right or wrong," O'Brien said. "When the so-called sting operations are done, what is the credibility of the people who do this?" he asked, adding that the company address was of Dubai. He claimed foreign funds were coming to the company. The TMC leader said that "my issue is much bigger", and added that the company had made five telephone calls to Dubai on the day that the "so-called" sting operation video was released. "We would like professional journalists to have the right to do any kind of investigation," O'Brien added. Urging the government to immediately order a probe into the matter, CPI-M general secretary Sitaram Yechury said, "This is a scam of the highest order." He said perhaps there was a "match-fixing" between the government and the Trinamool Congress on the issue. "The government should order an investigation... Why are they not ordering an investigation?" he said. "If the government is not responding, the chair has to protect the dignity of the house and order a house probe," the CPI-M member said. "When Tehelka tapes came (during the Vajpayee government), their leader (Mamata Banerjee) and their party had walked out of the BJP government," Yechury said. A sting operation by a news portal allegedly showed several Trinamool Congress leaders accepting money in return for lobbying for a private firm. Pushed to the wall on the sting controversy both in parliament and outside, the Trinamool Congress questioned the credibility of the video footage and hinted that foreign money was involved in creating these videos. As the Trinamool and Left members clashed, some CPI-M members trooped into the well of the house. Rajya Sabha Deputy Chairman P.J. Kurien told agitating Trinamool members, "What's the point fighting when he (Yechury) is only demanding an investigation! What is your objection over it?" The zero hour, however, went on amid the ruckus.