The leader of the Islamic militant group Hezbollah said Friday that it had captured three spies, two of whom were recruited by the C.I.A. to work for Israel. In a televised speech, the leader, Hassan Nasrallah, said that C.I.A. agents at the American Embassy in Beirut, Lebanon, had recruited at least two Hezbollah members and that the group was investigating whether the C.I.A. or another foreign agency had recruited a third. “We now have proof that this embassy is a spying nest and that some U.S. diplomats are intelligence officers penetrating and recruiting Lebanese society and Lebanese political factions,” he said. The American Embassy denied the allegation. “These are the same kinds of empty accusations that we have heard repeatedly from Hezbollah,” it said in a statement.