NEW DELHI, OCT 19: The petroleum ministry today admitted that release of Rs 18,000 crore petro-bonds to the national oil companies would be delayed by at least a month as the finance ministry has to take sanction of parliament for this budget neutral measure. Responding to newspersons queries, the Petroleum Secretary Vijay Kelkar said: "We had discussions with the finance ministry and I understand they will require parliamentary approval . It will be sorted out within a month." The petroleum minister, Janeshwar Mishra had announced last month that government would issue of petro-bonds worth Rs 18,000 crore to oil companies to bridge the massive oil pool deficit.The non-convertible petro bonds, announced as a one-time measure, would convert the liabilities of oil companies to assets in their books and the oil companies could borrow upto Rs 5,000 crore against the bonds.