Officers of public sector oil companies have threatened to launch an indefinite strike from September 5 to press for their demands of salary hike."Despite repeated pleas, we have not heard from the government even once. So we have decided to launch an indefinite strike from September 5," Oil Sector Officers' Association (OSOA) convener Ashok Singh said.OSOA is a representative body of executives of all public sector oil firms. The body had submitted a memorandum to Prime Minister Manmohan Singh on August 4.Public sector oil employees are demanding pay revisions every five years, 100% dearness allowance neutralisation with effect from January 1, 1996, 50% DA merger, and immediate release of additional stagnation increments.The association is also seeking an entry level salary of Rs 50,000 per month (from Rs 20,000 per month) for management trainees and commensurate rise in emoluments at senior levels.Sources in the Petroleum Ministry said the ministry has already made its recommendations to the Department of Public Enterprises (DPE) favouring the demands of the oil PSU officials. "It is now up to the DPE to take a decision on the issue," the sources said.