Portugal is one of five countries that the European Union executive deems “pose a risk of non-compliance”, according to the European semester documents released in Brussels on Wednesday. The others are Belgium, Austria, Slovenia and Italy.

The commission had already written to Portugal’s finance minister, Mário Centeno, citing concerns about the deficit reduction measures foreseen for next year, which it said fell short of what had been agreed. It asked for clarification on how the government aimed to meet euro-zone rules.

In his response, Centeno wrote that the difference in the estimates of potential gross domestic product on which the calculations of the government and the commission are based "is not statistically significant".

At issue is the structural adjustment projected for 2018, which the government has said will be equivalent to 0.5% of GDP, but which the commission calculates at just 0.4%. The EU had recommended that Portugal make an adjustment of 0.6%.