Indonesia's government says China has agreed to conduct a joint feasibility study regarding the extension of a railway that was launched last month.

The 140 kilometer high-speed train route between the capital Jakarta and the city of Bandung started operating on October 2. The new plan is to extend the line by 500 kilometers to the second largest city of Surabaya.

Indonesia's state enterprise ministry says the two countries signed a joint study agreement for the extension project last month.

China won the bid for the original project after a fierce battle with Japan. No financial burden was initially placed on Indonesia, but the costs ballooned to 7.3 billion dollars. Jakarta ended up covering some of the expenses.

The construction of a semi-fast train line between Jakarta and Surabaya is a separate project. Indonesia and Japan signed a feasibility study regarding its construction in 2019. But no major progress has been made on the project.

President Joko Widodo has said that the Indonesia-Japan project is still in the study stage. The government is considering whether or not it should be excluded from the national strategy project.