GENEVA — Turkey’s president declared on Friday that Turkish troops would remain in Cyprus “forever,” complicating hopes of reuniting the island nation, which has been effectively partitioned since 1974.

“Greece is fleeing again from a solution to the Cyprus problem,” the president, Recep Tayyip Erdogan, told reporters in Istanbul on Friday. “Turkey will be in Cyprus forever.”

That said, Mr. Erdogan often takes a firmer line with domestic audiences than with foreign ones, and diplomats said they remained cautiously optimistic.

In 1974, a coup sponsored by the military junta that controlled Greece at the time ousted the government of Cyprus, and Turkey invaded, arguing that the Turkish Cypriots needed its protection. The nation has been largely stable and peaceful for decades, but this is one of the world’s thorniest and longest conflicts.