People pack a street in Itaewon in central Seoul as many come out to enjoy Halloween festivities, Oct. 31. Yonhap

The Seoul city government will conduct safety inspections on all densely populated areas as part of measures to prevent a possible crowd surge, officials said Friday, in the wake of the deadly Halloween tragedy that killed at least 156 people, mostly in their 20s.

Some of the areas include a famous entertainment district surrounding Gangnam Station in southern Seoul and others near Hongik University and Yonsei University, called Hongdae and Sinchon, respectively. The areas are best known for clubs and restaurants among young people.

Notably, the city government will look into unauthorized building structures in the areas after criticism arose that the illegal extension of a hotel at the Itaewon crush site could have aggravated the disaster.

Police officers patrol the streets of Gangnam District in this July 12, 2021 file photo. Yonhap

Hamilton Hotel allegedly constructed a terrace in a downhill alley ― located near Itaewon Station that connects to a slew of bars and clubs from the main road ― causing a section of the narrow alley to become even narrower.

The city government also said it has launched an inspection into some the city's most populated subway stations such as Sindorim and Sadang.

Some parts of the city's metro system have been referred to as "hell" by commuters as stations and trains are packed with large crowds during rush hours. (Yonhap)