ATHENS, Greece — Senior banker Lucas Papademos was named today to be the new prime minister of an interim Greek unity government that seeks to cement a new European debt deal and stave off national bankruptcy.

Papademos, who was named after four tortuous days of power-sharing talks, immediately called for unity and promised to seek cross-party cooperation to keep Greece firmly in the 17-nation eurozone.

The 64-year-old former vice president of the European Central Bank was chosen to lead a temporary government backed by both the governing Socialists and opposition conservatives that will operate until early elections, tentatively set for February. He replaces outgoing Prime Minister George Papandreou midway through the Socialist leader’s four-year term.

“I am not a politician but I have dedicated most of my professional life to exercising financial policy both in Greece and in Europe,” Papademos said after the Greek president gave him the mandate to form a Cabinet. “The Greek economy continues to face huge problems despite the great efforts than have been made for fiscal reform.”

He insisted Greece must defend its euro membership.