As many as 140,000 residents in Lleida, in Segrià, have been ordered to stay in their homes and only leave for food or essential work. Officials have banned eat-in restaurants, weddings and meetings of more than 10 people as part of the new lockdown measures. The town is located 100miles west from Barcelona.
Seven nearby municipalities in the Segrià region have also been ordered to go back into lockdown.
The regional government decided to tighten its existing restrictions following a rise in coronavirus cases.
People have bene banned from leaving their homes except to buy food, go to the bank, or for work if it is an "essential service" and cannot be done from home.
Meetings of more than 10 people and weddings have also been banned, while restaurants have been told they can only do home deliveries.
Last weekend the entire Segrià region, which is home to about 400,000 people, was ordered back into lockdown.
The earlier rules were not as strict as the ones imposed today, and sought to restrict the number of people entering or leaving the region.
But the regional government was forced to tighten its restrictions after a recent surge in coronavirus cases.
Catalonia has registered 816 new cases in the past 24 hours.
The Segria region is said to have accounted for 190 of the total.
Just two days ago the Catalan government ruled out introducing stricter lockdown measures, after it said the mandatory use of face masks should help combat the spread of the virus.
At the time, a local official said: "We are not envisaging a total lockdown. People cannot be locked away indoors.
"The use of face masks in public is now mandatory at all times but we can't have police officers watching everyone so individual responsibility is very important."
People living in A Marina along Spain’s northern coast in the province of Lugo are also not able to leave the area.
The region of Galicia imposed restrictions on about 70,000 people last Sunday following a fresh coronavirus outbreak.
Additional reporting by Gerard Couzens
More to follow…