A new evacuation order has been issued as the largest wildfire in British Columbia continues to challenge efforts to bring it under control.

The BC Wildfire Service says the blaze north of Kamloops now covers 402 square kilometres and flames on one of its flanks surged toward control lines Monday.

An evacuation order for nine more properties near Savona has been issued, adding to the 170 already ordered out by the Thompson-Nicola Regional District and the Skeetchestn Indian Band.

In the south Okanagan, the wildfire sparked Sunday east of Skaha Lake now covers nine square kilometres but firefighters say it is burning away from the community of Okanagan Falls, allowing local authorities to lift evacuation orders.

Residents of 77 affected properties have been allowed to return home, but must be ready to leave on short notice as evacuation alerts remain in place for nearly 700 properties along the southeast corner of Skaha Lake, south of Penticton.

More than 300 wildfires are currently burning across the province and Environment Canada says heat warnings or special weather statements will remain until at least Wednesday, advising of temperatures in the mid to high 30s for a large, already parched area of central and southern B.C.