The Vietnamese contractor was originally hired, in 2005, to undertake tunnelling works under a US$2.1M contract with VGR Bao Loc.
Cavico said that the bulk of the extra money - US$2.2M - was for additional construction work, including managing the concreting works. The balance is for rising costs of fuel and materials.
It added that the first instalment of the extra payment was expected to be approximately US$0.7M. The remainder is to be paid upon completion of the project, scheduled for the end of this year.
The company said it is in advanced stages of negotiations on cost adjustments on a number of other projects.
