San Francisco, Aug 31 (IANS): The US Department of Agriculture Forest Service will close all 20 million acres of California's national forests to the public for two weeks from Tuesday dur to the raging wildfires in the states.

A statement signed by California's Regional Forester, Jennifer M. Eberlien, said the authority had made the difficult decision "to better provide public and firefighter safety due to the ongoing California wildfire crisis", reports Xinhua news agency

This closure was scheduled to start from Tuesday until September 17, the statement said.

Last week, Forest Service's nine national forests in Northern California had been closed due to extreme fire conditions throughout the state and strained firefighting resources throughout the country.

Monday's statement also disclosed that more than 6,800 wildfires had burned 1.7 million acres, an area larger than the state of Delaware, across all jurisdictions in California, and the National Wildfire Preparedness Level (PL) had been at PL5 since July 14.

It was only the third time in the past 20 years that the nation reached PL5 by mid-July -- indicating the highest level of wildland fire activity.

According to CAL Fire, excessive heat warnings are in effect for much of California and could present additional challenges.

Fires are also burning across the western US in Washington, Oregon, Idaho, Montana, Utah, Colorado, Wyoming, Arizona, and New Mexico, according to InciWeb.

In Minnesota, a number of fires are burning in Superior National Forest near the Canadian border, including the Greenwood Fire, which has scorched more than 25,900 acres and is only 14 per cent contained.