The cancellations affect the 2A, 2C and 70 Arriva services between Wrexham, Oswestry and Shrewsbury.
Arriva said the cancellations were because of "increased staff absence" and a spokesperson confirmed the absences were related to cases of Covid-19.
On social media the company said: "Due to increased staff absence the following 2A and 70 buses will not run: bus 2A 11.08am from Oswestry to Wrexham; bus 2C 12.22pm Wrexham to Cefn Mawr; bus 2A 1.37pm 2A Wrexham to Oswestry; bus 70 14.12pm Oswestry to Shrewbury; bus 70 3.15pm Shrewbury to Oswestry; bus 70 4.12pm Oswestry to Shrewbury."
Simon Mathieson, area managing director for Arriva, said: "We have unfortunately had to cancel some of our services in Oswestry and are working hard to ensure that we can keep as many services running as possible. We’d like to thank all of our customers for their understanding and ask that you check our Facebook and Twitter pages for the latest services updates."