A strengthening economy is good news for President Mauricio Macri ahead of mid-term elections in October, after a moderate expansion of 0.3 percent in the first quarter and a decline of 2.3 percent in 2016.

"The economy is growing and is now at the levels of December 2015," when Macri took office, said the source who refused to be named.

The source said consumption grew 4.8 percent in May, helping drive growth.

The government has previously said 2017 growth will be around 3 percent.