Senior Congress leader Kapil Sibal on Saturday slammed the Prime Minister's silence on major banking scams unearthed in the country over the last few days and termed Narendra Modi the "most expensive chowkidar" in the world."Modiji used to give a statement everyday against the Congress when a (2G) scam worth Rs 1.76 lakh crore was alleged during the UPA regime.That was a presumptive loss. Later, the court said there was no scam at all," Sibal said while briefing the media here. Referring to the banking frauds by diamond jeweller Nirav Modi (worth Rs 11,300 crore) and others (Rotomac loan default worth over Rs 3,000 crore) as "actual" losses, Sibal said: "Why is he (Prime Minister) silent now?"Modi spoke about the bank fraud for the first time on Friday at the ET Global Business Summit saying government would take "stern action" against irregulaties."He (Narendra Modi) gets a house, a plane; he is the most expensive watchman in the world," he added.The former Union Minister said that the Prime Minister should explain why these scamsters "gained" while the nation faced losses under his watch."Several leaders in the Bharatiya Janata Party have connections with these scamsters, who have left the country," he said.