The money should be obtained from other sources, with the government balancing its budget, said Nguyen Duc Hai, Chairman of the National Assembly's (NA) Finance and Budget Committee, the agency with authority to approve payments from the central budget.

The government had asked the NA to allocate VND4 trillion from the central budget to pay money it owed the Hanoi -Hai Phong Expressway contractor. 

The government was supposed to pay project investor Vietnam Infrastructure Development and Finance Investment Jsc (VIDIFI) over VND4 trillion ($171 million) for land clearance, VND4.7 trillion ($201 million) in land use fees collected in the Gia Lam Urban Area in Hanoi near the expressway, and another $300 million for a loan VIDIFI had taken from a South Korean and a German bank.

These sums would come from a fund of VND10 trillion ($427 million) earmarked for important national projects under the country's 2016-2020 public investment plan, the government said in its proposal.

It said that drawing money from the earmarked funds was "feasible" as it was in line with central budget obligations and National Assembly resolutions.

However, the National Assembly disagreed, saying that VND10 trillion was prioritized for projects to reinforce dyke systems or river bank erosion, and to pay compensation for ground clearance for urgent projects operating under the central budget.

"While prioritised projects do not have capital for completion, it is not reasonable to allocate 40 percent of these funds to pay off land clearance compensation and resettlement debt accrued by the Hanoi-Hai Phong Expressway project," Hai said.

The expressway, which connects the capital with the northern port city, was completed in 2015 in the form of a build-operate- transfer (BOT) project costing VND45 trillion ($2 billion).

The government needed to invest 30-50 percent of that amount or VND13-22 trillion ($556-941 million), but failed to do so in full because of budgetary limitations.

It promised to pay the money with land use fees and rentals collected in urban areas and industrial zones built near the expressway after the project was completed.

The Hanoi – Hai Phong Expressway is among Vietnam's biggest transport infrastructure projects. According to VIDIFI, it serves over 27,000 vehicles each day on six lanes that allow speeds of up to 120 kilometers an hour.