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The extension was expected and has been the practice of all U.S. presidents dating to the 1970s under a section of the so-called "Trading With the Enemy Act."
Obama extended the embargo even though he has made reaching out to old U.S. foes a key plank in his foreign policy.
There have been signs of a possible thaw in U.S.-Cuban ties since Raul Castro early last year took over as president from his ailing brother Fidel. Fidel Castro had held the post since heading the revolution that ousted the U.S.-backed Batista regime on Jan. 1, 1959.
Obama has sought to reach out to Cuba by easing travel and financial restrictions on Americans with family in Cuba. The two countries have said they will hold talks on resuming direct mail links. But Obama has also said he will not lift the embargo until Cuba undertakes democratic and economic reforms.
In signing the extension, Obama was taking a symbolic step because existing law, the Helms-Burton Act, requires Congress to take action specifically ending the embargo.
But Obama also bypassed an opportunity to suggest a willingness for easing U.S.-Cuban animosity.
The White House statement renewing the provisions was dated Sept. 11 but only released on Monday, when the last extension, issued by former President George W. Bush, was to expire.
"I hereby determine that the continuation for one year of the exercise of those authorities with respect to Cuba is in the national interest of the United States," Obama said in a memorandum addressed to Secretary of State Hillary Rodham Clinton and Treasury Secretary Timothy Geithner.