UPDATE: BUSHFIRES continue to burn out of control in Victoria's alpine parks and in Gippsland.

And authorities warn the fires could it flare up again later this week, with worsening fire conditions forecast for Friday.

The alpine fire, now two separate blazes, has burnt more than 16,800ha in the north, while the alpine south fire has so far destroyed at least 8400ha.

According to the Department of Sustainability and Environment, these fire were not directly threatening lives or property earlier this week.

But smoke from the blaze was blanketing northeast Victoria.

Backburning is continuing, a State Control Centre spokeswoman said, as the weather was expected to worsen later this week.

"The fire risk is looking high for Thursday and very high for Friday,'' she said.

"We're advising people to be vigilant and enact fire plans if required.

"At the moment the advice is only to watch and act for all these fires.''

With 300 firefighting personnel are now tackling the blaze.

Today fire crews are planning significant burns along the south eastern and southern section of the Harrietville-Alpine South fire.

Crews also will work to strengthen containment lines along the Dargo-Kings Spur track on the southern edge.

Meanwhile, the Aberfeldy-Donnellys fire in Gippsland continues to burn and has consumed more than 82,800 hectares.

Fire Services Commissioner Craig Lapsley said with no rain forecast and the conditions very dry, fire risks remained high for "the next few weeks''.

Temperatures are forecast to be in the low to mid 30s late this week, with fire danger forecast to be high or very high for most of the state.

Firefighters are also preparing for potential lightning strikes later in the week.