He told a National Assembly discussion on land administration and use that it would help prevent arbitrary changes to land planning.
Deputy Prime Minister Trinh Dinh Dung had earlier expressed concern about the increasing population density in urban areas such as Hanoi and Ho Chi Minh City, which are receiving an additional 200,000 people each year.
If in five years they have to house an extra one million people, there would be too much pressure on their infrastructure, he said.
Dung blamed this partly on changes made to urban regulations to suit the interests of investors, saying they should also have been based on the practical needs of the public and government.
He said there is public frustration from arbitrary changes made to construction density, the number of floors permitted and population density.
The proposal to set up the land planning portal was welcomed by Minister of Natural Resources and Environment Tran Hong Ha, whose ministry manages land.
Ha said the establishment of such a portal and publicizing of all land transactions would help create average prices for land within five to 10 years. "Then, land valuation will be more transparent and scientific."
Dung said control over land use and urban planning would be strengthened so that development takes place in a planned and systematic manner.
"We must identify priority projects to prevent adjustments that are arbitrary or not in line with approved plans. This will ensure the real estate market develops healthily."
The government would tighten control over the selection of investors for urban projects and make sure land valuation is transparent and in line with the market mechanisms to avoid losses to the state budget, Dung noted.
"Land administration will be streamlined and effective. Officials committing violations will be penalized in accordance with the law."
Figures from the General Statistics Office show that at the end of 2018 Hanoi and Ho Chi Minh City had populations of 7.78 million and 8.64 million respectively.