Radiation from nuclear accidents such as Chernobyl and Fukushima may not present as much of a threat to wildlife as previously thought, British researchers say.

Earlier studies on the impact on birds of the catastrophic nuclear accident at Chernobyl in Russia in April 1986 have been put in doubt by new research, the University of Portsmouth reported Wednesday.

The findings by Portsmouth researcher Jim Smith and colleagues from the University of the West of England are likely to also apply to wildlife at Fukushima in Japan following its nuclear disaster in 2011, the university said.

"I wasn't really surprised by these findings -- there have been many high profile findings on the radiation damage to wildlife at Chernobyl but it's very difficult to see significant damage and we are not convinced by some of the claims," Smith said.

"We can't rule out some effect on wildlife of the radiation, but wildlife populations in the exclusion zone around Chernobyl have recovered and are actually doing well and even better than before because the human population has been removed."

Previous studies had suggested radiation affected bird populations following the Chernobyl disaster because it damaged to birds' antioxidant defense mechanisms, but the new research found the birds' antioxidant mechanisms could easily cope with radiation at density levels similar to those seen at Chernobyl and Fukushima.

The researchers said their finding would likely apply to other forms of wildlife as well.

"We would expect other wildlife to be similarly resistant to oxidative stress from radiation at these levels," Smith said.