Firefighters continue Saturday morning to battle a 225-hectare blaze burning just outside the northeast edge of Algonquin Park, between the park and Canadian Forces Base Petawawa.

On Friday afternoon, the Ministry of Natural Resources (MNR) said the fire had been upgraded from a category two or three fire to a hotter, faster category four fire spreading at a rate of about five metres per minute.

The fire grew from 150 hectares to about 225 hectares during that time, ministry spokesman Doug Skeggs said on Saturday.

But by Friday's evening hours, falling temperatures and rising humidity slowed down the spread of the fire, Skeggs said.

The fire is burning close to Barron Canyon Road in the remote ranges of a military training area that covers about 340 square kilometres. It was first spotted on the base at about 2 p.m. ET Thursday, according to CFB Petawawa public affairs officer Sally-Ann Cyr.

Cyr would not confirm if there was a military exercise underway when the fire was spotted. Exercises were taking place, but not in the area that the fire was detected, Cyr said. The training area includes a firing range.

By Saturday morning, the fire in some places was about 100 metres away from the edge of Algonquin Park, Skeggs said.

The fire is contained, Skeggs said, but is not yet under control.

Entire eastern portion of park evacuated

By about 6:15 p.m. ET Friday an evacuation notice was issued, affecting the eastern portion of the park.

About 400 campers and canoers in the area were given four hours to pack up and leave. Skeggs said evacuation efforts were continuing Saturday and "going well without incident."

Campers were being told to stay at their sites so camp wardens can find them quickly if the area needs to be evacuated, should the fire jump the Petawawa River.

Military firefighters from the base continue to battle the blaze with the aid of provincial firefighters from Ontario and Quebec.

Two MNR fire behaviour analysts are also projecting the movement of the fire using computer models based on the weather.

Bulldozers have cut lines into the woods surrounding the fire, Skeggs said, to help prevent it from spreading.

Several water bombers have been used to contain the fire. No injuries or property damage have yet been reported.

The base's fire station is equipped with three tankers and anywhere from seven to 13 firefighters, said Cyr. She said all available fire crews were being deployed.

On Thursday, the park had issued an open fire ban for campers as a precaution, because dry conditions in the region had made the area susceptible to brush fires.