The United States hopes to conclude aviation talks with Cuba about the resumption of scheduled commercial airline flights "very, very soon," a senior U.S. State Department official said on Tuesday.

The official was speaking ahead of Thursday's one-year anniversary of the United States and Cuba's agreement after 18 months of secret talks to restore diplomatic ties that Washington severed more than 50 years ago.

"We do hope to achieve a successful outcome of these negotiations very, very soon. It would be wrong of me to pinpoint exactly when, but we certainly hope before the end of the year, if not sooner," said the official, who spoke to reporters on condition of anonymity.

In September, a State Department official said among the key civil aviation issues that had to be discussed were aviation safety and security. The U.S. Federal Aviation Administration and Transportation Security Administration must sign off on Cuba's operations. Direct charter flights have served Cuban-Americans and specialist groups for travel to Cuba for years.

Even with a flight agreement, travel to Cuba by Americans would still be limited by the U.S. economic embargo that bans general tourism to the communist-ruled island.