The Office of Fair Trading (OFT) has said the European Commission was best placed to review IAG's proposed acquisition of Lufthansa's UK unit bmi and that there is no need for a separate British review of the deal.
But the consumer watchdog said it would continue to work closely with the EC to assess whether the deal raises competition concerns for airline passengers including those travelling to and from airports in Scotland and the North West of England to London's Heathrow airport.
Late last year, British Airways owner IAG agreed to buy bmi for £172.5m, seeing off rival bidder Virgin Atlantic in the race to grab loss-making bmi's coveted runway slots at Heathrow.
Virgin Atlantic last month made a formal complaint to the EC about the deal, saying competition on some European routes would diminish and that fares would increase.
The OFT said the EC should consider the deal because the impact of the acquisition on the overall competitive position at London's Heathrow airport requires a comprehensive review of routes across many jurisdictions, not just those in Britain.