"In the case of such megaprojects, it is essential to keep track of the prices of different components, such as construction work and materials, bridges and viaducts, ecoducts and environmental alleviation measures, which may change over time," Rail Baltic Estonia CEO Indrek Orav told BNS.

"While AECOM's 2011 analysis calculated that the railway would cost approximately €3.8 billion to build, figures concerning the aforementioned components as well as the exact route and technical solution are known by now, and therefore the cost can be calculated considerably more precisely than back in 2011," he explained.

"Compared to 2011, the overall cost of the project has increased and totals approximately €5 billion," said Orav. "Adding the construction of the Kaunas-Vilnius connection, we get a cost of around €5.8 billion. The cost of the Estonian section has remained stable in recent years at about €1.3 billion, of which the Estonian state's co-financing would account for €250-300 million."

At a press conference last October, project coordinator RB Rail CEO Baiba Rubesa said that the total cost of Rail Baltic may amount to €5 billion. As recently as last May, however, the overall cost of the project was estimated to be €3.68 billion.

Rail Baltic is the project for the construction of a European-gauge high-speed railroad from Tallinn to Lithuania's border with Poland.