US and Cuban officials said on Wednesday they had made important headway in a months-long effort to restore scheduled flight service between the countries after half a century of confrontation.An agreement would pave the way for US airlines to schedule flights to Cuba that travelers could book directly from their websites, which could boost tourism and business on the Communist-ruled island.A formal deal has yet to be reached, the officials said. The Associated Press, citing unnamed officials, reported earlier on Wednesday that the United States and Cuba had reached "an understanding" on restoring commercial airline flights.The negotiations come on the eve of the anniversary of the Cold War foes' decision to normalize relations, which led to prisoner exchanges and the opening of embassies in Washington and Havana.Josefina Vidal, director of US affairs at the Cuban Foreign Ministry, said the countries "obtained important advances in the negotiation" and that "soon we will be able to make an announcement."A US State Department official said the two countries were making progress but still negotiating.Delegations from the countries convened on Monday in Washington for the latest round of talks on aviation, following negotiations in March and September. Scheduled commercial flight service has been suspended for decades as a result of Cold War animosity, although charter flights have connected the countries in the interim.US President Barack Obama has relaxed travel restrictions since last year's detente. That has led to a boom in US citizens' visits to Cuba, which are up 71 percent this year, with 138,120 Americans arriving over the first 11 months.General US tourism to the island remains banned by the US trade embargo of Cuba.The market would grow further if the US Congress were to lift either the tourism ban or the embargo.Major US airlines including JetBlue Airways Corp, American Airlines Group Inc, Delta Air Lines Inc and United Continental Holdings Inc have all expressed interest in scheduled service to Cuba.