Iran could soon increase uranium enrichment in an underground nuclear plant, diplomats say, a development that may further complicate efforts to resolve peacefully a dispute over Tehran‘s atomic ambitions. Iran has nearly finished installing centrifuges at the Fordow enrichment plant buried deep inside a mountain and is believed to be in a position in the near future to significantly step up production there of material that could be used for bombs if processed further, they said. “They should be able to (increase production) within a few weeks,” one diplomat accredited to the Vienna-based U.N. International Atomic Energy Agency (IAEA) said on Thursday. Fordow is of particular concern for the West as Iran uses the facility to refine uranium to a fissile concentration of 20 percent, a short technical step from bomb-grade material. The fact that it is buried deep underground also makes it less vulnerable to any air strikes, which Israel has threatened if diplomacy fails to stop Iran getting nuclear weapons capability.