FRANKFURT, March 30 (Reuters) - The European Central Bank could skew its bond purchases towards greener assets but should not be responsible for developing the new benchmarks for climate-friendly quantitative easing, Dutch central bank chief Klaas Knot said on Tuesday. The ECB has bought over 280 billion euros of corporate debt in the past five years to keep borrowing costs low but critics say its asset purchases disproportionately benefit polluters as these firms are over-represented in the bond markets. Proposals under consideration as part of the ECB’s strategy review include skewing purchases especially towards green assets or penalizing the biggest polluters. “That’s something we should absolutely consider,” Knot told an online conference organised by the Financial Times. “My preference would be for us not to come up with an allocation ourselves, but that there would be a somewhat better benchmark developed outside the central banking world that we could then use to tilt these purchases.” The ECB could act as a catalyst in creating new methodologies, Knot argued, but more corporate disclosure is required and credit rating agencies also need to incorporate climate risk in their assessments. The ECB now buys bonds in proportion to market capitalisation but several prominent officials, including ECB chief Christine Lagarde and board member Isabel Schnabel have questioned the value of market neutrality. “This is all about imperfect pricing, a sort of market failure and we could only get better pricing of climate-related risk once there is more data, more information, out there. And that’s why we stimulate the harmonisation of disclosure standards,” Knot said. (Reporting by Balazs Koranyi; Editing by Catherine Evans)