International Consolidated Airlines Group, otherwise known as IAG, saw passenger growth accelerate strongly in June, according to statistics released by the British Airways and Iberia owner on Wednesday. Group traffic measured by revenue passenger kilometres (RPK) - a key performance indicator in the airline industry - rose by 8.2% last month, compared with June 2012. Capacity measured by available seat kilometre was up 7.4% year-on-year.The airline had suffered from subdued traffic numbers during the spring, with RPK falling 2.4% in February, rising 0.1% in March and dropping 5.6% in April, as the company was hit by strikes by Iberia employees and the timing of Easter.Traffic recovered strongly in May, rising 7.4% on the prior year. The stock was trading 1.27% lower at 263.9p before the close of trade on Wednesday, broadly in line with the wider market.Nevertheless, the shares have risen strongly since the start of the year, jumping around 42%, relatively immune to the market volatility that has hammered the benchmark FTSE 100 over recent months.