International Consolidated Airlines' (IAG) stock slumped as cabin crew at its UK carrier British Airways threatened to strike over salary conditions.The staff said they were prepared to take industrial action after their pay claims were rebuffed.A ballot last week showed 95% of crew were in favour on going on a strike. Those threatening strikes are mainly younger crew, employed under inferior terms and conditions to pre-existing crew.The airline said that it is still involved in talks over pay and strike action is "completely speculative". Shares closed down 1.22% to 379.90p. RD