The southern expressway is meant to link the capital Colombo with the town of Matara in the deep south of the island which has suffered decades of neglect.
The project is already delayed by several years.
Around 35 percent of the highway has now been built but another 130 -150 million US dollars will be required to complete the work on schedule, said R W R Premasiri, General Manager of the Road Development Authority.
The government is still seeking the funds to build the 30 kilometre stretch from the port town of Galle to Matara.
Talks are underway with the Asian Development Bank and a Korean firm to get the required funds, Premasiri told our sister news website Vimasuma.
com.
It would be difficult to complete the expressway on schedule if the required funds for the Galle to Matara section are not found, he said.
The planned expressway starts from Makumbura near Kottawa, a suburb of Colombo, and links the town of Godagama in Matara.
Funds to build the section from Kotta