DUBAI, May 15 (Reuters) - Here are some factors that may affect Middle East stock markets on Thursday. Reuters has not verified the press reports and does not vouch for their accuracy.INTERNATIONAL/REGIONAL* GLOBAL MARKETS-Asian shares step back from highs, bonds supported MKTS/GLOB* U.S. crude, Brent hit 3-week highs on Cushing, gasoline draw O/R* Platinum, palladium set to extend rally; gold hol