BUDGET airline Ryanair is to be investigated by the Office of Fair Trading (OFT) after a string of complaints by an advertising watchdog, it has been revealed.

The Advertising Standards Authority (ASA) said its decision to refer Ryanair which flies from Durham Tees Valley and Newcastle airports - to the OFT followed "a catalogue of breaches"

of advertising codes and unwillingness to comply with rulings.

The authority had formally investigated complaints about Ryanair's advertisements and found them in breach on seven occasions over a two-year period.

It said the airline had persistently misled consumers by making exaggerated claims about the availability of flights at advertised prices, and advertised prices that did not include taxes and charges.

The airline had also made misleading and denigrating comparisons with competitors and had not stated restrictions that would exclude customers from taking up an offer, the ASA added.

A spokesman said the ASA rarely made formal referrals to the OFT, the most recent being in 2005, and only once it had established that an advertiser was unable to work within the rules.

Ryanair made its own complaint to the OFT last week over "unfair, biased and untrue" rulings against the carrier by the ASA.

Ryanair said the ASA had "demonstrated a repeated lack of independence, impartiality and fairness".