The move comes as the latest figures show that the numbers of people testing positive for coronavirus are continuing to rise across the north west and are well above the average rates north and south.
A total of 27 non-COVID patients who had been due to have procedures at Altnagelvin were affected up until Wednesday evening.
A spokesperson for the Western Trust said: “Due to a sudden increase in COVID-19 admissions to Altnagelvin Hospital in the last 24 to 48 hours and increasing rates of community transmission we had to reschedule a number of elective procedures.
“The situation is being managed in line with our surge planning and is being kept under constant review.
“We have been in contact with the patients affected.
“The Trust recommends members of the public get their vaccine and continue to follow social distancing and public health advice at this time.”
Latest stats show the Derry/ Strabane seven day COVID-19 rate has risen to 366.9 cases per 100,000.
Between June 30 and July 6, there were 555 cases giving a seven day rate of 366.9 per 100,000, up from 364.9 on Tuesday.
The average rate for the north is 161.3.
COVID-19 occupancy at Altnagelvin had also risen to 3.23% while at midnight on Tuesday there were sixteen coronavirus inpatients across the Western Trust.