* Export ban to be extended to March 15
* Ban was initially proposed from Jan. 24 for one month
* Ivorian tension sent cocoa to highest in about 30 years
(Adds statement extending ban to March 15)
ABIDJAN, Feb 22 (Reuters) - Ivory Coast presidential claimant Alassane Ouattara will extend until March 15 the period of the ban he has called on cocoa exports to try to unseat his rival, a statement from his government said on Tuesday.
The ban, initially proposed from Jan. 24 for one month, has been largely heeded by exporters even though Ouattara remains holed up in a hotel, while incumbent Laurent Gbagbo holds onto power in the top cocoa producing country.
"The government informs traders that the measure of suspending exports of coffee and cocoa is prolonged until March 15, 2011," the statement by Ouattara's Prime Minister Guillaume Soro said. "(It) reminds them that those who contravene this measure risk national and international sanctions."
Earlier Ouattara government spokesman Patrick Achi had said it would be extended until March 10.
Ouattara beat Gbagbo in a Nov. 28 presidential election, according to U.N.-certified results, but Gbagbo has refused to go, defying international condemnation and Western sanctions.
African leaders are currently in Ivory Coast seeking an end to the standoff but hopes of a breakthrough are low and the absence of West African leaders highlighted the difficulty of forging a united African position on the crisis.
Gbagbo retains the support of the military and controls most state institutions, including cocoa regulators and the ports.
But Ouattara has warned exporters that, assuming he comes to power, they would be sanctioned if they cooperated with Gbagbo's government by paying export taxes to ship their beans.
Exporters face the added dilemma of European Union sanctions on a number of Ivorian institutions backing Gbagbo and the combined measures have contributed to the drying up of exports.
The turmoil in Ivory Coast has driven cocoa futures to the highest levels in more than three decades. (Reporting by Ange Aboa; writing by David Lewis; editing by Anthony Barker)