Four former top Ho Chi Minh City officials are being investigated for alleged violations in the management and use of state properties, which investigators believe can be linked to notorious Da Nang tycoon Phan Van Anh Vu, who is in jail for revealing state secrets.

Former deputy chairman of Ho Chi Minh City Nguyen Huu Tin, who has been banned from leaving his residential area since Tuesday together with three former city officials, played a major role in the leasing of two ‘prime estates’ in the southern metropolis to a company owned by Vu without public auctions as required.

These include a piece of land at number 15 Thi Sach Street in downtown District 1, where Vu’s company has developed a shopping mall, services and apartment complex.

The estate is among 60 projects nationwide suspected of involving misuse of state-owned land by public officials, according to a list compiled by the Ministry of Finance and submitted to the government for review.

The complex’s location borders two downtown streets and is only a ten-minute walk away from the City Hall, which makes the 2,300-square-meter land plot highly valuable.

In June 2015, Tin signed a document granting the legal use of the land to Bac Nam 79 Constructions JSC, where Vu was board chairman.

In May 2016, the municipal administration approved the development of the project, and later green-lighted a proposal by Bac Nam 79 to change the use of the land, meaning to develop the mixed-use complex there.

The move shows signs of violating a 2007 prime minister decision, which stipulates that state-owned land can only be granted to a private party without public auction when there are no other applicants or when the land would be used for non-commercial purposes.

Dao Anh Kiet, who was director of the municipal Department of Natural Resources and Environment at the time, is also responsible for submitting the project to Tin for consideration and has been placed under house arrest since Tuesday for further investigation.

The second ‘prime estate’ linked to the officials’ alleged wrongdoings is a 1,300-square-meter plot of land located at number 8 Nguyen Trung Truc Street in District 1.

Despite a plan since 1999 to construct a children’s library in the area, in 2011 the municipal administration approved the leasing of the land to Bac Nam 79 for a period of 50 years following requests from the Ministry of Public Security.

After acquiring the legal use of the land, Vu’s company changed the estate’s purpose from cultural land to commercial land and began building a complex of high-rise office buildings and hotels.

The maximum height of buildings on the land was also approved to be raised by four times, from 20 meters to 80 meters.

Former chief of staff of the People’s Committee Le Van Thanh and former head of the urban division in the People’s Committee Office Nguyen Thanh Chuong were involved in procedures required for the land leases to go through.

Thanh and Chuong are the other two officials investigated in the same case.

The investigations are reportedly a result of the continuing probe into violations committed by Vu, 43, a disgraced business tycoon in Da Nang who was behind a number of shady real estate projects in Da Nang and Ho Chi Minh City.

He was in July sentenced to nine years in prison for “disclosing state secrets."

Vu is still under investigation for other charges including "tax evasion," "abuse of power”, and "violating regulations on the management and use of state-owned properties" in separate cases.