Mainland Greece could be removed from the UK Government's quarantine-exemption list this week, figures suggest.
The country is currently recording a seven-day rate of 20.5 Covid-19 cases per 100,000 people.
This is up from 17.7 a week ago.
A rate of 20 is the threshold above which officials consider triggering quarantine conditions.
Earlier this month the Government introduced a regional approach to its quarantine list which saw restrictions introduced for arrivals from seven Greek islands - but the rest of the country maintained its exemption.
Wales and Scotland have their own exemption lists which are similar but not necessarily identical to that created by the UK Government.
Iceland and Denmark also appear to be at risk of having quarantine measures introduced, with case rates of 68.6 and 63.2 respectively.
Other countries at or near the threshold include Sweden (20) and Italy (18.1).
Cyprus has seen its rate tick upwards to 8.9, compared with 3.3 a week ago.
The rates in the UK and Ireland are 44 and 38.6 respectively.
The figures have been calculated by the PA news agency based on data collected by the European Centre for Disease Prevention and Control.
Changes to the Government's list of countries from which arrivals in England do not need to self-isolate for 14 days are usually announced on Thursday at 5pm and implemented the following Saturday at 4am.
