Foreign Minister Edgars Rinkēvičs gave the estimate in an interview with Latvian Radio, while noting that there had been an increase in registering as the Brexit deadline approaches.
He said the data on Latvian citizens living in the UK is hard to pin down, "For a while it seemed that we had around 150,000 - 200,000 living in the UK, now the most recent statistical data suggests 117,000 at the moment."
According to the Foreign Ministry, 79,000 Latvians have now registered, a significant increase on the 16,000 who had registered in October last year. However about 40,000 more people still need to do so, the minister said.
He urged anyone who has not already done and wants to stay in the UK to apply on the relevant Home Office website, as problems may arise after the UK quits on 1 February.
For those who will not register by February 1, "there may be problems with work, they may have problems with their place of residence, and they may have problems with the authorities, who as one option may decide to deport them," the minister warned.
Registering would also help the work of the Latvian embassy in the UK, he added. Technically EU citizens still have until the end of June 2021 to apply for settled status.
Approximately 1.8 million citizens of European Union Member States have registered for UK long-term resident status after Brexit of around 3.3 million believed to be resident in the UK.
All citizens of the European Union (except Ireland), Iceland, Norway, Liechtenstein and Switzerland citizen and their families have to apply to the UK government's EU Settlement Scheme to continue living in the UK after 30 June 2021.
If an application is successful, people are then categorized into either settled or pre-settled status.