By Irwin Arieff UNITED NATIONS, Dec 20 (Reuters) - The U.N. Security Council renewed its ban on Liberian diamond exports for six more months on Wednesday after finding the West African nation could not yet track diamond-mining activity on its territory. A resolution adopted unanimously by the 15-nation council said it would again review in June Liberian efforts to ensure that so-called blood diamonds mined on its soil could not work their way into the mainstream gem market. The resolution also asked a panel of four outside experts to continue to monitor the government's progress and report back to the council by June 6 on whether the diamond embargo could be lifted at that time. The council imposed the embargo in 2001, two years before the end of Liberia's 14-year diamond-fueled civil war. Liberian President Ellen Johnson-Sirleaf, who took office last January, has pushed hard for an end to the embargo, saying the money from diamond sales was badly needed to finance reconstruction in her war-ravaged West African country. But the expert panel, in a report made public on Tuesday, told the Security Council that Liberia had not yet met the requirements of the Kimberley Process, a mechanism that requires participating governments to provide certificates for exports of rough diamonds to show they were mined from legitimate operations. The voluntary initiative between governments, the diamond industry and civic groups was launched in 2002 in hopes of ending the global trade in rough diamonds to finance wars against legitimate governments, as has occurred in Angola, Ivory Coast, the Democratic Republic of Congo and Sierra Leone. All four are participants in the initiative. The expert panel said Liberia had made progress toward fulfilling the Kimberley Process requirements but still needed to ensure its efforts led to "a coherent and functioning mechanism with long-term durability and credibility." With war behind it and a new government in place, Liberia was enjoying some of the fruits of a "fragile peace" and improving its management of state finances, the expert panel said. But it faces enormous reconstruction challenges and the government has been slow to demonstrate its campaign commitment to zero tolerance for corruption, it said.