The U.S. dollar is likely to continue rising until the current global economic slowdown stops and growth begins to accelerate, according to Citigroup Global Markets Inc.

The ICE U.S. Dollar Index, which tracks the dollar against its six global peers, has risen more than 18 percent this year, reaching its highest annual data gain since 1972.

The strengthening dollar was a major theme at meetings of financial executives and central bank governors in Washington this week as the rapid growth of the U.S. currency exacerbates the economic problems facing governments around the world. Strategists say relief is still a long way off, especially after U.S. Treasury Secretary Janet Yellen said this week that the strengthening dollar is a logical result of different global monetary policy stances.

According to Citigroup, even the Fed's decision to slow rate hikes may not be enough to convince most investors to sell the dollar. According to strategists, improving global growth prospects remains key.