A wildcat strike at London's Heathrow deprived airport operator BAA of its busiest month ever, slowing July passenger growth to 2.2 per cent at its seven British airports.

"In the absence of strike action, it is estimated that BAA would have recorded an increase of 3 per cent and seen its busiest month ever," BAA said in a statement yesterday.

BAA, which handled 13.2 million passengers in July, also said it had launched a £425 million (€604 million) senior unsecured convertible bond, due in 2009 and bearing interest of 2.625 per cent a year.

Two-thirds of the capital raised will be used to call in early its 2004 bonds, which had a more expensive interest coupon than the new bonds, a bank source said. The remaining cash will go into its investment programme, including spending on its new Terminal Five at Heathrow.