The three additional months are needed to carry out new preliminary evaluations of investors before they can bid for the public-private partnership (PPP) work, according to a recent report the government made to the National Assembly.

Next year, the evaluations are expected to be completed by February, the contractor identified by August, and the tendering process completed by November, the report said.

In September the Ministry of Transport decided not to invite foreign bids for the eight sections of the expressway to be built under the PPP model, saying only a few qualified and this could lead to a low level of competition.

Sixty investors, half of them Chinese, submitted expressions of interest for the eight sections, but for four of them no investor met all the requirements, while for the rest only one to three did so, the ministry said in a statement.

It then decided to invite fresh tenders with lowered criteria for the North-South Expressway from local investors, to "ensure national security and expand Vietnamese firms’ capability in infrastructure construction."

Eleven sections of the transnational expressway, prioritized for this year, cost a total of VND118.72 trillion ($5.12 billion), of which VND55 trillion ($2.37 billion) will come from the government, and the rest from commercial loans, mainly from domestic banks, it said.

The 11 sections will run 654 kilometers between northern Nam Dinh Province near Hanoi and Vinh Long Province to the southwest of Ho Chi Minh City.

The expressway will be over 2,000 kilometers in all, and the estimated completion date is in 2025.