Russia will likely continue lowering its U.S. debt holdings as Washington struggles to contain a budget deficit and bolster a tepid economic recovery, a top aide to President Dmitry Medvedev said Saturday.

"The share of our portfolio in U.S. instruments has gone down and probably will go down further," said Arkady Dvorkovich, chief economic aide to the president, told Dow Jones in an interview on the sidelines of the St. Petersburg International Economic Forum.

Russian holdings of U.S. Treasury securities fell to $125.4 billion in April 2011 from $176.3 billion in October 2010, Treasury Department data showed.

Asked if U.S. debt was as solid an investment now as it was 10 years ago, Mr. Dvorkovich said: "On an absolute basis, yes. On a relative basis, compared to other investments, of course not."

"When we take decisions and compare, we're not thinking in absolute terms," he said.

Russia's financial reserves—which stood at $528 billion as of June 10—are the world's third largest, after China and Japan's. As of May, according to Russia's central bank, 47% of reserves were in dollars and 41% in euros, compared with 45.2% in dollars and 43.1% in euros on Jan. 1.

The central bank recently diversified the stash to include the Canadian dollar, which makes up 1% of the total, and plans to put 0.8% into the Australian dollar starting in September.

The Wall Street Journal