Information from the Portuguese Met office states that so far there are no reports of the quake having been felt.

The tremor happened at 4.48am and its epicentre was pinpointed at around 110 kilometres south of the coast of Faro.

An earthquake measuring 3.5 on the Richter scale was also registered on Sunday in the areas of Cadaval, Óbidos and Peniche, along Portugal's west coast.