A ceremony in Vietnam's largest city Ho Chi Minh City on Sunday celebrated the opening of the country's first subway, built with help from Japan.

About 500 people attended the event. The Japan International Cooperation Agency, or JICA, provided yen-denominated loans, and many Japanese companies were involved in the construction.

The 20-kilometer railway line, which is expected to ease Ho Chi Minh City's worsening traffic congestion and air pollution, connects the center of the city and its suburbs.

Part of the railway line is on elevated tracks and part of it is underground, making it the country's first subway.

A Vietnamese official said the project is a symbol of cooperation between the two countries, and shows that Japan's way of integrating technology and its management model was a success.

Many people took photos on the platform and inside the cars when the first train departed.

Ito Naoki, Japan's Ambassador to Vietnam, said he thinks the railway is a new symbol of bilateral cooperation that bore fruit as a result of collective efforts by the Japanese side. He said the project signifies further cooperation.