Portugal may reinstate some restrictions to stop the spread of the coronavirus in the run-up to the holiday season as Europe witnesses a new wave of infections.

Portugal's prime minister Antonio Costa, who spoke on the sidelines of an event in the country, said the measures would be only applied when "strictly necessary".

"We must try to act now so we can reach the Christmas period with less fear. The later we act, the greater the risks," Costa told journalists.

Government ministers are expected to meet health experts on Friday to evaluate the situation and only then will decide on which rules to impose.

A lockdown is unlikely, according to Costa, and the new measures would aim to "disturb people's lives as little as possible".

Mask-wearing is still required in public transport, shopping malls and large gatherings while the EU digital COVID-19 certificate is required to enter nightclubs and big events, in addition to traveling.

Portugal has experienced a gradual rise in the number of new cases over the past month, reaching a two-month daily high of 1,816 new infections on Saturday.

The 14-day infection rate stood at 156 cases per 100,000 people on Monday, about double that in neighbouring Spain, which has a slightly lower share of its population fully vaccinated, but still well below over 500 in Germany and more than 900 in the Netherlands.

Portugal is one of the world's most vaccinated nations with close to 86 percent of its population of just over 10 million fully vaccinated against COVID-19.

Portugal has reported about 1.1 million cases and 18,265 deaths since the pandemic began.

(With input from Reuters)