LONDON, July 14 (Reuters) - The United Nation's maritime arm said on Monday it would decide this week whether to adopt tough new European Union laws outlawing some single-hulled oil tankers globally or shelve the idea altogether. The International Maritime Organisation (IMO) said it would debate the far-reaching proposals at its Marine Environment Protection Committee meeting this week. "Changes to (the) Marine Polution Convention (MARPOL) will be considered. IMO could go ahead with them or could reject them altogether," a spokeswoman said. Industry experts consider the meeting to be one of the most critical in recent years as the decision will shape the future of oil transportation at a global level. The EU, shocked by the economic and environmental devastation wrought by the sinking of the Prestige oil tanker in November, is pushing to outlaw the transportation of all heavy grades of oil on single-hulled ships by September. It also proposes radically accelerating the phase-out of all single-hulled tankers, much to the bewilderment of the IMO which has its own global timetable for phasing out old and potentially dangerous oil tankers. A spokeswoman for the IMO reiterated that it disapproved of "unilateral or regional" action on the basis that it damaged the concept of universal regulation; discriminated against other regions; confused the industry and had a negative impact on the supply of oil. The IMO said it had already appointed a team of experts to undertake an impact study on the tougher regulations should they be introduced. The report, which has not been made public, takes into account criteria like the volume of oil traded on the world's oceans and the number of single-hulled vessels available. The spokeswoman said a working group had been set up to discuss the finer points of the changes ahead of a final decision on Friday. Some 125 nations have signed up to the MARPOL Convention, representing 97 percent of the world's tanker fleet.