Barroso, who was also prime minister of Portugal from 2002 to 2004, formally took early retirement when he stepped down in 2014 after two terms as head of the commission.

“A former member of the commission has the right to a lifetime pension from the date that he reaches the age of 65 [but] can ask that this pension start being paid at the age of 60," the official said.

In that case, the official explained, “a reduction coefficient is applied” that in Barroso's case is 0.7, meaning that the former commission president should be receiving a little over €7,000 a month.

Portugal's current prime minister, António Costa, on Friday said that he had requested "clarifications" from Barroso's successor as European Commission president, Jean-Claude Juncker, that there would be no "discriminatory treatment" of the former president, given that commission rules do not bar him from taking up the position at Goldman Sachs.

Barroso had earlier accused the commission of discrimination after it ordered an ethics probe into his new role.

The fact that he is going to Goldman Sachs has drawn criticism, including from Juncker and other senior EU officials, because of the role that the US bank is seen to have played in the global financial crash and the euro-zone debt crisis.