Many of these projects deviated from the approved design or failed to comply with urban planning, Le Thanh Nam, director of the city Department of Natural Resources and Environment said at a recent meeting with Hanoi voters.
Some developers illegally added floors or have yet to complete their financial transactions commitments, he said.
The department has sought the issuance of title deeds by the city for 33,000 of the apartments, he said.
The developers would be penalized for their violations, he promised.
Many apartment owners have been complaining that they have not received the title deeds for years, making it difficult for them to sell or use them as collateral at banks.