A rendering shows a new subway station to be on Line No. 9, near the Godeok Gangil New Town 1 residential complex. (Seoul Metropolitan Government)

The Seoul Metropolitan Government said Tuesday that its plan to extend Seoul Subway Line No. 9 farther east side of the country's most populous city has been approved by the central government.

Under the plan worth 640.8 billion won ($504 million), the capital city looks to add four more subway stops along a new 4.1-kilometer branch of Line No. 9, stretching out of VHS Medical Center Station, located in Gangdong-gu, Seoul.

The new last stop would give the Godeok Gangil New Town 1 residential complex greater access to the public transit system. New Town 1 aims to accommodate over 1,300 households beginning in early 2024.

One of the stations in between, Godeok, is to serve both Line Nos. 5 and 9 as a transfer station. Another stop will sit next to Hanyoung Foreign Language High School.

The fourth phase of Line No. 9 is poised to start operations in 2028, following six years of construction. Seoul said the plan, submitted to the Ministry of Land, Infrastructure and Transport in August, won state approval in December.

Line No. 9 began operation in 2009 after its first phase of construction, connecting western Seoul near Gimpo Airport and an area in Gangnam. It runs both local trains and express trains. The line has since extended eastward in two more stages.

Upon completion of the fourth phrase, Line No. 9 will stretch 45.5 kilometers across Seoul along the south side of Han River, according to the municipal government.

The city now runs nine subway lines, some of which reach outside Seoul.

"Residents of eastern Seoul will enjoy greater access to business districts Gangnam and Yeouido, tackling inconveniences due to inadequate transport infrastructure and stimulating the economy of the eastern Seoul area," Kim Seong-bo, assistant mayor of Seoul Metropolitan Infrastructure, said in a statement.

The subway extension plan is one of two announced by the Transport Ministry, along with the bus rapid transit extension project worth 41.9 billion won connecting Bokjeong Station of Line No. 8 and Namhansanseong in Gyeonggi Province.