WENN - Rockers AC/DC's controversial Austrian concert in May is facing a further setback: Government officials have warned that unexploded World War II bombs at the site pose a threat to the 80,000-strong audience.

The band is set to play Wels Airport on May 22 despite animal rights activists threatening legal action against the group if they go ahead with the show, as it could threaten colonies of nesting rare birds.

But it was revealed on Wednesday that the airport had been the target of heavy bombing during the war, and city chiefs are worried this could prove dangerous for fans.

Experts on bomb defusing and de-mining are set to evaluate the site and present their reports to the city government before a decision is made as to whether the gig can go ahead, according to Wels' deputy mayor Hermann Wimmer.