BRASILIA (Reuters) -South American bloc Mercosur has concluded talks for a free-trade agreement with a group of four European nations known as EFTA, sources from the Brazilian government said on Tuesday.

An announcement is expected on Wednesday during a Mercosur summit in Buenos Aires, the sources said. Despite the agreement in principle, the deal would still lack internal approvals from the countries involved to come into effect.

EFTA and Argentina, which currently hold the Mercosur presidency, did not immediately respond to requests for comment outside normal business hours.

Talks on an agreement between the European Free Trade Association (EFTA) group of four non-EU nations - Norway, Iceland, Switzerland and Liechtenstein - and Mercosur, which includes Brazil, Argentina, Uruguay, Paraguay and Bolivia, have been happening since 2017.

An agreement was announced in 2019, but it did not advance amid disagreements on environmental issues.

Mercosur and the European Union reached an agreement for a free trade deal last year, which has faced pushback from countries such as France and which also lacks approval by member nations.

One of the sources said that, unlike the Mercosur-EU agreement, no resistance for a deal is expected from countries of the EFTA group.

Reuters reported last year, citing sources, that an agreement with EFTA was among the most likely to be signed by Mercosur this year.