ATHENS — Greek trade unions launched a general strike and nationwide protests on Tuesday against a new package of austerity measures, to be voted on this week, which would condemn Greece to more years of hardship in exchange for rescue loans.

Flights to and from the country stopped for three hours at the start of a 48-hour strike that closed schools, halted train and ferry services, and left Athens without public transport or taxis while state hospitals ran on emergency staff.