In a statement, Moody's said Portugal's "economic and fiscal performance remained in line with expectations."

Moody's last assessment of Portuguese sovereign debt was in May, when it kept Portugal's rating unchanged, at 'A3', with a 'stable' outlook.

The rating agency also highlighted that the "economic and fiscal outlook remains solid".

In the same note, Moody's also highlighted some challenges such as the public debt ratio, although it pointed out that it has been decreasing.

Analysts consulted by Lusa expected Moody's to keep the rating unchanged, but to improve the outlook.

In September, Fitch decided to keep Portugal's rating unchanged at "A-", but revised the outlook upwards to "positive". Click to read the report here.

A month earlier, Standard & Poor's (S&P) also maintained Portugal's rating at "A-", with a positive outlook.