LONDON (Reuters) - Blackstone Group LP (BX.N) has agreed that annual payments of $325 million would be made for 30 years to the Reuters News business as part of an offer by the U.S. private equity firm to buy a majority stake in Thomson Reuters’ (TRI.N) (TRI.TO) Financial and Risk unit, two sources familiar with the matter said on Tuesday. Blackstone would own 55 percent in the new company and Thomson Reuters would retain a stake of 45 percent.