NEW DELHI: As industrialist Vijay Mallya fights his wilful defaulter tag, former CAG Vinod Rai has said Kingfisher Airlines ' loan default is just a "trickle" and the overall problem of huge bad loans at public sector banks can be blamed on 'cronies' using connections to borrow money.Rai, who was the Comptroller and Auditor General (CAG) during 2008-2013, has also stressed the need to understand the trend of non-performing assets of private sector banks being very low in comparison to that of public sector lenders.Observing that cronies have neither the domain knowledge nor the financial strength to deliver, Rai in his new book has said that they use their connections to borrow from the banking sector, especially from public sector lenders that are prone to manipulation."This is the underlying reason for non-performing assets (NPAs) of public sector banks going up manifold," he has written in the book titled 'The Dairy of the Nation's Conscience Keeper -- Not Just An Accountant'."Stories of Kingfisher Airlines and Bhushan Steel are only now emerging in trickles. The amount that has gone into corporate debt restructuring is another story; it contains all the marquee names," he said.On September 1, state-owned UBI declared Kingfisher Airlines, its promoter Vijay Mallya and three other directors wilful defaulters. Kingfisher owes about Rs 7,000 crore to 17- banks consortium, led by State Bank of India.Last month, a consortium of banks ordered a forensic audit into the books of account of cash-starved Bhushan Steel, which has total exposure of about Rs 40,000 crore to lenders.The move came close on the heels of the arrest of Bhushan Steel Vice Chairman and Managing Director Neeraj Singal by the CBI in an alleged cash for loan scam involving Syndicate Bank Chairman S K Jain.According to Rai, Reserve Bank of India (RBI) data showed that gross NPAs of public sector banks increasing to 3.61 per cent, which by all standards marked unprecedented high levels in 2013."Even if we were to accept the argument that these banks had to advance money in difficult times, why is it that the NPA of private sector bank is only half this percentage? It does not require much analysis to ascertain the reasons," he noted.Further, the former CAG has raised concerns about the appointment process at public sector bank boards."Many of those who bemoan the malfeasance that has crept into appointment processes, are aware of the names of the nominee government directors on public sector bank boards, and the absence of 'fit and proper' criteria for their nomination."However, few take steps to correct the situation. Somewhere, someone will have to take the bull by the horns. The process cannot be delayed by even a day," Rai said.