FARES on British Airways flights between Glasgow and Heathrow shot up by more than one-third after struggling airline bmi withdrew from the route last year, Sir Richard Branson has claimed.

The Virgin Atlantic president said passengers travelling between Scotland and the UK's busiest airport could expect further fare hikes and service withdrawals if a proposed takeover of bmi by BA's parent company goes ahead, saying the deal would "take British flying back to the dark ages".

His comments came after business groups raised concerns that passengers travelling on routes from Heathrow to Aberdeen and Edinburgh will suffer under the deal as it will hand BA an effective monopoly.

But they were rebuffed by International Airlines Group, formed by the merger of BA and Spanish airline Iberia last year, which pointed out it had increased the number of Glasgow-Heathrow flights by 25% after it became the sole operator on the route.

In a submission to the European Commission, which is expected to rule on the deal next month, Virgin Atlantic pointed to industry data showing BA's Glasgow-Heathrow fares increased by 34% in the six months following bmi's withdrawal from the route.

A spokeswoman for IAG declined to comment on the allegation that the fares had risen by that figure.

It stated that it offered "highly competitive" one-way fares. She said IAG was confident regulatory authorities would approve the deal.