More than 2% of Portugal's population has emigrated in the past two years, since the country entered recession.
Emigrant secretary Jose Cesario said up to 240,000 people had left since 2011.
Most were young, educated people moving to Switzerland or Angola, a former Portuguese colony.
He said more would probably have emigrated had job prospects in Europe not taken a turn for the worse.
Mr Cesario said between 25,000 - 30,000 people left for Angola in 2012, adding that the figure was between 5,000 - 10,000 higher than in the previous year.
The BBC reports the numbers going to Mozambique were also growing fast.
Only Europe's economic slowdown and high level unemployment in other EU nations had kept overall emigration from being far higher, Mr Cesario said on Friday.