Fire crews hope to get Marlborough's massive forest fire fully contained by the end of the day.

The blaze is into its seventh day, with crews managing to get it about 90 percent contained yesterday.

Incident controller John Foley says even if they achieve their goal today, there's still plenty of work ahead of them.

"It's 440 hectares of burning area so it's going to take a while to get it to a stage where we're happy that it's not going to blow out but unless we get any significant rain, we've basically still got a fire sitting there."

Foley said another 50 crew members will join the operation today to battle the blaze.

"We've brought in some additional forestry crews that are hill fit for that type of terrain and they'll be put into those more difficult sectors that need those type of hill fit people."

Even if crews get the fire fully contained today, Foley said they still have weeks of work ahead of them to fully extinguish it.