The Ministry of Natural Resources and Forestry says Kenora Fire 51 has now grown to over 28,000 hectares in size.
The blaze is located near the Ontario/Manitoba boundary about 100 kilometres northwest of Kenora.
The ministry has remapped the fire, which has been active over the past several days producing a lot of smoke.
A dozen fire crews and eight helicopters have been assigned to the blaze.
In the meantime, there were 10 new forest fires Tuesday, bringing the number of actives to 77 in the region.
Twenty-five are considered not under control.
The Red Lake district was busy one again with three new starts.
Three were also discovered in the Sioux Lookout region.