(SOFIA) - Bulgaria will open up several major ports, airports and train stations to private investment to speed up modernisation of its ageing infrastructure, Transport Minister Alexander Tsvetkov said Tuesday.

The freight terminals of Bulgaria's two largest airports, in Sofia and the southern city of Plovdiv, will be opened up to private investors in coming months, together with four other airports, Tsvetkov told a press conference.

Concession offers will also be made on parts of the two key Black Sea ports in Varna and Burgas, along with the Danube ports of Ruse, Silistra, Tutrakan, Nikopol, Vidin and Lom.

Several train stations, including those of Sofia, Plovdiv and Varna, will also be offered to potential investors, Tsvetkov added.

The concessions will concern projects that cannot be funded by European Union aid, the minister said.

Bulgaria hopes to benefit from as much as two billion euros (2.68 billion dollars) in EU transport aid by 2013 but this has to be used to improve infrastructure along five so-called Pan-European transport corridors that criss-cross the countryy.

So far, Sofia has only got access to about 2.5 percent of the money, with the rest held up by EU demands for clear oversight of the funding in the face of corruption concerns and a lack of projects.

Bulgaria, which spans a territory of 111,000 square kilometres (42,857 square miles), has just 418 kilometres (260 miles) of major highways and poor infrastructure is often cited by foreign investors as a major obstacle to doing business.