Key things to know about the Oregon militia standoff

A group of armed protesters are occupying a wildlife outpost in the US state of Oregon leading to a standoff with the authorities.

The men, who are asking militia members around the country to join them, took over the Malheur National Wildlife Refuge following a peaceful rally on Saturday in support of members of a local family who are facing additional jail time for arson.

Here is what we know about the occupation, known as the Oregon Militia Standoff.

• How did it begin?

Tension has been building for weeks in the Burns, Oregon, area over the case of Dwight and Steven Hammond. Father Dwight Hammond, 73, and his son Steven, 46, said they lit fires on federal land in 2001 and 2006 to reduce the growth of invasive plants and protect their property from wildfires.

They were convicted three years ago - Dwight for three months and Steven for one year. But in October, a federal judge ruled their terms were too short and ordered them back to prison for about four years each.

The decision has sparked an angry reaction in the community and those outside it including Ammon and Ryan Bundy, sons of Nevada rancher Cliven Bundy, who are leading the protest.

• Who are the Bundys?

Ammon and Ryan Bundy are the sons of Nevada rancher Cliven Bundy, who was involved in a standoff with the government's Bureau of Land Management over grazing rights in 2014. They are among those leading the opposition to the federal government at the wildlife refuge.

Ammon Bundy and approximately 100 militiamen from other states arrived last month in Burns, some 60 miles from the Hammond ranch.

On his Facebook page, Ammon Bundy called other militia men and "all patriots" to stand up for the Hammond family. He has criticised the US government for what he called a failed legal process.

The protesters have said that they are willing to stay in the federal buildings for "as long as it takes". Ryan Bundy told the Oregonian that many of the men were willing to fight and die to protect the rights of states, counties and individuals to manage local lands.

• How has the Burns community reacted to the standoff?

The Malheur National Wildlife Refuge is about 30 miles south of Burns in in the high desert of eastern Oregon. The area is very remote, about 280 miles southeast of Portland.

Many locals have told the outside groups to stay away, concerned their presence could lead to violence.

The Hammonds have said that the Bundys and other protesters do not speak for them. Their attorney, W. Alan Schroder told KOIN: "Neither Ammon Bundy nor anyone within his group or organisation speak for the Hammond family."

Dwight Hammond has said he and his son plan to peacefully report to prison on Monday as ordered by the judge. "We gave our word that's what we would do, and we intend to act on it," he told The Associated Press.

• How have the authorities reacted?

Harney County Sheriff Dave Ward has told people to stay away from the area as authorities work to defuse the situation.

Beth Anne Steele, an FBI spokeswoman in Portland, told the AP agency was aware of the situation at the national wildlife refuge but made no further comment.

But on social media many are questioning why there has not been a more forceful government response to the incident under the hashtag #OregonUnderAttack.

In a statement on its Facebook page, the Malheur National Wildlife Refuge said that it will continue to "monitor the situation".