Shipbuilder Austal has won a $US19.9 million contract extension to provide support services for the shallow water combat ships it is building for the United States Department of Defense.

Austal said the modification to the contract exercised options to provide class service efforts, special studies, analysis and review of the $4.8 billion Littoral Combat Ship (LCS) program.

Austal chief executive Andrew Bellamy said the company’s USA-based subsidiary would assess engineering and production challenges and evaluate the cost and schedule risks for the program.

Works are expected to be complete by March 2014.

“This award is important as it aligns with Austal’s strategy of expanding the level of support services we provide, in particular for the US Navy’s LCS and Joint High Speed Vessel (JHSV) platforms for which we are prime contractor,” Mr Bellamy said in a statement.

Austal holds two significant contracts with the US Navy; a $1.6 billion deal to construct 10 joint high speed vessels; as well the 10-ship LCS deal.

At 12:20PM, WST, Austal shares were up 0.75 per cent, trading at 67.5 cents.