* Cameco, CNNC unit have deal for 23 mln lbs by 2020 * Cameco shares down in early trading March 13 (Reuters) - Canada's Cameco Corp will begin exporting uranium to China soon, according to the premier of the resource-rich province of Saskatchewan. Saskatchewan-based Cameco signed an agreement in 2010 to supply China Nuclear Energy Industry Corporation, a unit of China National Nuclear Corporation (CNNC), with 23 million pounds of uranium concentrate through 2020. Saskatchewan premier Brad Wall told reporters on Tuesday that both the Canadian and Chinese governments have approved the deal, and have an agreement on nuclear co-operation in place. That agreement ensures monitoring to verify that Canadian uranium is used for civilian purposes, such as generating power. "We should be moving uranium into that market very soon," Wall said, in comments to reporters that were recorded by his office. "Basically, every hurdle has been cleared." The uranium deal is worth C$1 billion ($971 million) at current prices, and could lead to mine expansions, Wall said. A Cameco spokesman was not immediately available for comment. The company's shares were down nearly 3 percent in early trading in New York and Toronto. CNNC is China's largest generator of nuclear power, while Canada is the world's second-biggest uranium producer, after Kazakhstan. A CNNC delegation visited Saskatchewan on Tuesday. Wall said uranium mining will be a theme in Saskatchewan's 2013-14 budget, which his Saskatchewan Party government will unveil next Wednesday.