(Adds Obama's upcoming meeting with Ukraine prime minister)
WASHINGTON, March 9 (Reuters) - The United States will not recognize the annexation of Crimea by Russia if residents of the region vote to leave Ukraine in a referendum next week, U.S. national security official Tony Blinken said on Sunday.
Crimean officials have called a vote for next Sunday to confirm that the region, which has an ethnic Russian majority, is a part of Russia in the wake of the ouster of Ukraine's Moscow-allied president last month.
Blinken, U.S. President Barack Obama's deputy national security adviser, said on CNN's "State of the Union" program that Russia would come under increased international pressure as a result of the referendum in Crimea.
"First, if there is an annexation of Crimea, a referendum that moves Crimea from Ukraine to Russia, we won't recognize it, nor will most of the world," Blinken said.
"Second, the pressure that we've already exerted in coordination with our partners and allies will go up. The president made it very clear in announcing our sanctions, as did the Europeans the other day, that this is the first step and we've put in place a very flexible and very tough mechanism to increase the pressure, to increase the sanctions."
Obama will meet with Ukrainian Prime Minister Arseny Yatseniuk at the White House on Wednesday to discuss a resolution to the Crimea situation.
Obama has said a referendum on Crimea would violate international law and the Ukrainian constitution. Last week he announced sanctions including travel bans and freezing of assets of individuals responsible for Russia's military intervention in Crimea. Russian President Vladimir Putin was not among the individuals.
Russian forces have seized the Crimean peninsula, crucial to Moscow as warm-water port and home to its Black Sea naval fleet, with a bloodless occupation that has elevated tensions with the West to their highest level since the Cold War.
Representative Mike Rogers, the Republican chairman of the House Intelligence Committee, questioned the effectiveness of sanctions against Russia.
Rogers said on ABC's "This Week" program that Germany's economic and energy ties to Moscow could make its own economy vulnerable if sanctions bite deeply on Russia.
"You've got some problems with sanctions and how that works out and how they (Germany) can go forward without screwing up their own economy," he said.
Rogers said Putin had shown an "expansionist attitude" and that the United States should not underestimate "the kinds of things that he will do that he thinks is in Russia's best interests."
Representative Paul Ryan, appearing on CBS's "Face the Nation," suggested targeting the oligarchs who back Putin and boosting U.S. natural gas exports as a way of cutting into a crucial Russian business in Europe. (Reporting and writing by Bill Trott; Editing by Jim Loney and Meredith Mazzilli)