A massive forest fire raged out of control Friday in southern Chile, forcing the closure of a famed national park after destroying thousands of hectares of pristine Patagonian steppe.

High winds fanned the huge blaze at the Torres del Paine National Park, where Chilean President Sebastian Pinera said 8,500 hectares (21,000 acres) of woodland and scrub had already been ravaged by the flames.

The Chilean government has deployed four planes and a helicopter to the remote mountainous region, where 300 firefighters, soldiers and forest rangers were engaged in a desperate effort to get the inferno under control.

Pinera pledged another 100 personnel would join crews on Saturday and said his government would seek "all necessary assistance" from other countries, having already contacted Argentina, Australia and the United States.

Argentina, which has its own Patagonian preserves just across the border from Torres del Paine, has already sent in some emergency teams.

"We are faced with a hugely complex situation, an extreme scenario, mainly due to topography, strong winds and highly combustible vegetation," said Vicente Nunez, head of Chile's Office of National Emergency (ONEMI).

The wildfire, believed to be caused by humans, has grown dramatically since Thursday when just 1,500 hectares (3,700 acres) of land was burnt. Some 700 people, mostly tourists, have been evacuated from the park.

The blaze erupted late Tuesday and advanced rapidly in dry conditions, forcing authorities to close the park, which is located some 3,000 kilometers (1,860 miles) south of Santiago.

Glaciers and Andean lakes lie alongside natural forests and the Patagonian steppe at the 2,400-square-kilometer (927-square-mile), semi-desert nature preserve visited by several thousand tourists each year.

A 2005 bush fire started by a Czech backpacker destroyed 160 square kilometers (62 square miles) of the park.

Late December is peak season for hikers in Torres del Paine and officials said the current blaze was very likely the result of human negligence. The park will remain closed for all of January, Pinera said.