Chile's president Tuesday ordered extra funds to be spent on tackling what she called the country's worst forest fires ever, as other countries sent aid and firefighters to help.

Flames have destroyed 155,000 hectares (600 square miles) of land in the center of the country and at least 4,000 people have been evacuated, the National Emergency Office said.

President Michelle Bachelet visited the disaster zone Tuesday and said she had ordered the Treasury "to seek additional resources to fight the fire and deal with what comes afterward, since many families have lost everything."

Some 4,000 emergency workers are fighting the fires, with about 36 separate blazes still active on Tuesday, a week after the first ones broke out, the emergency office said.

Bachelet said specialists had arrived from France to help fight the blazes, which have prompted the government to declare a state of catastrophe.

The fires have struck mainly in sparsely populated rural areas in the central regions of O'Higgins and El Maule.

The United States offered $100,000 for the firefighting effort and Mexico has sent personnel.

Bachelet said the Walton family, owners of US retail giant Walmart, were paying for a Boeing 747 to join in fighting the flames.

Bachelet on Monday called it "the biggest forestry disaster in our history."

Three firefighters have died and another three have been wounded battling the flames.

Bachelet scrapped a trip to the Dominican Republic for a summit of Latin American and Caribbean leaders on Wednesday in order to oversee the firefighting effort.

Fires are common in Chile's parched woods during summer. Most are caused by human activity.

But this year was considered worse because of a drought that has built up over the past eight years, attributed by environmentalists to climate change.