(Reuters) - Nebraska Governor Pete Ricketts issued a state of emergency declaration on Thursday, after federal agriculture officials confirmed a second farm site had tested positive for the rapidly spreading avian flu virus, according to state officials.

The declaration follows earlier, and similar, actions by governors in Wisconsin, Minnesota and Iowa, whose states have all been hard hit by the bird flu outbreak that had impacted more than 33 million birds across the United States.

Ricketts' move opens the door to release emergency funds and other aid to the Nebraska Department of Agriculture and other state agencies that are trying to contain the bird flu outbreak, which has now affected more than 3.5 million egg-laying hens in Nebraska.