WASHINGTON (Reuters) -Britain believes there is more work needed to secure broader agreement on international tax commitments made by G7 wealthy democracies in the coming weeks and months, a senior UK official said on Thursday. Jonathan Black, Britain’s G7 and G20 sherpa, told an online forum hosted by the Center for Strategic and International Studies in Washington that it will be naturally more challenging to win consensus among G20 major economies for G7 agreements on a global minimum corporate tax and new methods of taxing large multinational firms. “The prize is huge. I think we are sort of optimistic, actually, that we will make progress on this but there’s still important work to be done in the next few weeks, and if not that, certainly, then, over towards the end of the year as well,” Black said. G20 finance leaders are expected to endorse a global corporate minimum tax when they meet July 9-10 in Venice, according to an early communique draft seen by Reuters, but the document makes no mention of the 15% or higher rate endorsed by G7 leaders earlier this month. The G20 document calls for technical work on the new tax framework to be completed in time for implementation by G20 meetings in October. Black said that the G20, which includes China and India, is a body with much more varied interests and values than G7 countries that include Britain, Canada, France, Germany, Italy, Japan and the United States. White House deputy national security adviser Daleep Singh, who serves as the U.S. G7 and G20 sherpa, told the forum that despite divergent values, G20 group economies had shared interests on international tax among other issues. Reporting by David Lawder;Editing by Chizu Nomiyama and Howard Goller Our Standards: The Thomson Reuters Trust Principles.