Eight countries, including Turkey and the Maldives, were also removed from the government’s red list.
According to the independent travel company’s recent booking figures, Spain (20%) and Greece (13%) are "firm favourites" for a late summer break in September and October 2021.
The countries are also the most popular destinations for winter 2021/22 and summer 2022.
Following the recent government announcements, Travel Counsellors reported a 24% upsurge of new bookings for winter 21/22 as well as a 20% increase in new bookings for summer 2022, led by Greece, Spain and the USA.
Kirsten Hughes, UK managing director for Travel Counsellors, said the company’s priority is to ensure that customers "continue to travel safely".
"However, like the rest of the industry, we have been calling for clarity on the traffic light system and testing requirements, which have been very confusing," she added.
"Today’s announcement is a step forward in making travel a bit easier and more accessible. Whilst still not offering us the freedom we had before the pandemic, the new two-tier travel system will make it a lot clearer to the travelling public which countries they can book a holiday to.
"We are already seeing that customer confidence is going up and we are truly enjoying seeing so many more customers going abroad and enjoying their well-deserved break."
