LONDON (Bloomberg) — Ryanair Holdings Plc, Europe's biggest discount airline, plans to sue the European Commission for not investigating complaints over state aid to national airlines Air France-KLM Group and Deutsche Lufthansa AG.Air France, Lufthansa, Alitalia SpA and Olympic Airways SA received hundreds of millions of euros in illegal state assistance, the Dublin-based airline said yesterday in a statement.

"Ryanair is confident that the European Court will take the commission to task for their failure to fairly enforce the state aid rules against national governments who continue to protect their inefficient flag carrier airlines," Jim Callaghan, Ryanair's head of regulatory affairs, said in the statement.

The European Commission, the European Union's antitrust regulator, ruled in February 2004 that Ryanair was benefiting from illegal aid at Belgium's Charleroi airport. The airline was ordered to pay back a portion of the aid, which included discounted landing and ground-service fees as well as incentives for opening new routes to the airport.

Ryanair is in disputes with UK airport operator BAA Ltd. and Dublin airport owner DAA over the landing fees the companies charge airlines and expansion plans. The carrier also intends to appeal a commission decision to block its [EURO]1.48 billion ($2.02 billion) hostile bid for Irish airline Aer Lingus Plc.

"It looks like load factors in Ryanair's legal department are running close to 100 percent at present," Joe Gill, an analyst at Goodbody Stockbrokers in Dublin with a "buy" rating on the stock, said in a note to investors yesterday. "Although a rant, the Ryanair statement does underline uncomfortable home truths about national governments blatantly protecting their flags, especially those whose finances are hopeless, like Alitalia and Olympic."

After the 2004 Ryanair ruling, the commission drew up rules that said governments must seek to earn a profit on the subsidies they dole out to airlines and airports.

The commission is confident that it acted "fairly and effectively," spokesman Martin Selmayr told reporters in Brussels yesterday. The organisation will study the complaints carefully as soon it receives notification of Ryanair's court case, Selmayr said.

Ryanair accused the French government of giving discounted airport fees to Air France, Europe's biggest airline. Germany's Munich airport is losing money while building a new terminal for Lufthansa, the region's second-largest carrier, Ryanair said.

In southern Europe, the commission "has rubberstamped multi-billion bailout packages for Alitalia," and the Greek government has given "massive injections of state aid" to Olympic, Ryanair said.

Callaghan accused the commission of a "twin-track approach to state aid," refusing to take action against national governments assisting flag carriers, "while at the same time they launch bogus investigations against small regional and secondary airports like Charleroi".

Companies have stepped up suits against the commission for failing to start investigations into both illegal state aid and alleged abuses of monopoly power. There are four pending lawsuits at the Court of First Instance in Luxembourg.

They can make several legal arguments. They can try to convince EU judges that the commission treated their state aid case differently from competitors, such as finding against Ryanair while ignoring illegal aid for flag carriers.

"That's a very tough standard," said Eric Morgan de Rivery, a Paris-based partner at Jones Day who specialises in EU competition law. "It's extremely difficult to argue."

Companies could also try to prove that national airlines benefited from political support and governments granted special rights to flag carriers, such as favorable landing slots or space at an airport. The commission could then be forced to open a probe.