NHS England figures show 191 people had died in hospital at Buckinghamshire Healthcare NHS Trust as of 5pm on Sunday (January 3).
That was an increase of three compared to Friday, when there were 188.
It means there have been 11 deaths in the past week, up from six the previous week.
The victims were among 5,945 deaths recorded across the South East.
Daily death counts are revised each day, with each case backdated to the actual date of death.
This means some of the deaths that were first recorded in the latest period may actually have taken place days earlier.
NHS England guidance states: "Confirmation of Covid-19 diagnosis, death notification and reporting in central figures can take up to several days and the hospitals providing the data are under significant operational pressure."
Only deaths that occur in hospitals where the patient has tested positive for Covid-19 are recorded, with deaths in the community excluded, such as those in care homes.