Aer Rianta is believed to have expressed tentative interest in investing in a new airport project in Berlin, where negotiations with potential developers are nearing conclusion.

The State-owned company, which has operations in and part-owns the airports at Düsseldorf and Hamburg, is thought to be willing in principle to participate in the €3.5 billion venture. The company also owns 48.25 per cent of Birmingham airport.

Talks between the states of Berlin and Brandenburg and a consortium involving the property group IVG Holding and construction group Hochtief have been ongoing in recent months. Brandenburg premier Mr Matthias Platzeck yesterday said the parties were close to a successful end to negotiations.

Hochtief has close links with Aer Rianta and is partner to the Irish company in its two German operations. Aer Rianta paid €2.54 million for a 7.2 per cent stake of Hamburg airport two years ago; Hochtief owns 28.8 per cent. The Irish company is thought to have paid in excess of €44.44 million for its share of a 50 per cent stake in Düsseldorf, jointly held with Hochtief.

While the two companies expressed interest in acquiring a stake in Turin airport three years, they withdrew their bid. Last year Aer Rianta also examined possible involvement in Sydney airport. At that time, the company said it was consolidating its assets rather than expanding them.

While negotiations on the construction of the Berlin project are not complete, Aer Rianta is expected to enter the process if Hochtief seeks a partner to operate the airport. The project is designed to provide Berlin with a large, modern airport to replace the three smaller hubs that serve the city.

Hochtief and IVG would bear the costs of the project in return for operating the airport and taking its profits for 50 years.

Under the existing plan, Berlin-Brandenburg Airport, as it will be called, will open in 2008, when Berlin's Tegel and Tempelhof airports will close. However, that date might be shifted to 2011 when a viable minimum of 20 million passengers per year are expected.

In addition to its shareholdings in foreign airports, Aer Rianta has duty-free shops in Europe and the Middle East.