Economists say this turnaround is largely due to a strong rebound in tourism, which reached record levels last year following the lifting of pandemic travel restrictions.
The sector is key for the three nations, accounting for almost 25 percent of Greece's economy, and 12 percent in both Portugal and Spain.
The trio of nations are also benefiting from the EU's massive pandemic recovery fund, whose mix of grants and loans in exchange for structural reforms will largely go to southern countries.
Spain -- the biggest beneficiary of the fund after Italy -- has so far received 38 billion euros, Greece 15 billion euros and Portugal eight billion euros.
The three nations have also made "great efforts to improve their economic attractiveness" with structural reforms that have boosted their competitiveness and improved their labour markets, said Darvas.
The reforms have helped draw foreign investment, especially in renewable energy and cloud computing.
Amazon's cloud computing division AWS announced last month it would invest over 15 billion euros to expand its data centres in Spain.
Many automakers such as Volkswagen and Stellantis, whose brands include Peugeot, Fiat and Jeep, have chosen to assemble their new electric vehicles in Spain, Europe's second largest automobile producer after Germany.
