Russia abruptly signaled on Thursday it would extend a grain export ban until late 2011 and ordered authorities to prevent speculators driving up food prices after the worst harvest in years. Prime Minister Vladimir Putin's surprise statement on the export ban -- which had been due for review after Dec. 31 -- puzzled analysts and helped send benchmark Chicago wheat prices higher, Reuters reported. "I would like to note that the lifting of the export ban can only be considered after next year's crops have been harvested," Putin told a government meeting. Amid speculation that he might have misspoken, his spokesman confirmed the statement. Russia banned grain exports from Aug. 15 to Dec. 31 as a historic drought drove grain harvest forecasts down to about two-thirds of last year's figure, stoking fears of sharp food-price increases that could become a political liability. In a sign of jitters, President Dmitry Medvedev ordered law enforcement agencies to stop speculators driving up prices and and pledged help to ensure affordable food staples. Putin's statement indicated the grain export ban would be extended by many months. Russia will harvest next year's crop by November 2011. Surprised analysts said Putin might have meant to refer to the 2010 harvest. "It may well be a slip of the tongue," said Andrei Sizov Sr, CEO of SovEcon agriculture analysts. But Putin's spokesman Dmitry Peskov, asked whether Putin meant the ban could not be lifted until next year's crop is harvested, told Reuters, "That was what was announced by Putin." The Kremlin has sent mixed signals about the ban. Medvedev said last month the ban could be lifted before its planned Dec. 31 expiry, depending on the harvest while Putin had said it could last into 2011. This year's harvest is expected to fall to 60-65 million tonnes, after what the state weather agency says is Russia's worst drought in over a century ,from 97 million tonnes in 2009, although officials say there is enough grain to feed the people.