JAKARTA - Indonesian President Joko Widodo launched construction on Wednesday for a new line on Jakarta's mass rapid transit (MRT) system, funded by a loan of nearly $1 billion from Japan, in a bid to alleviate traffic congestion.

Sometimes paralyzed by some of the world's worst traffic jams, Jakarta is home to more than 10 million, but three times the number live in surrounding towns, and it launched its first MRT line in 2019.

Expected to be completed by 2031, the new line will run 25 km between the city of Bekasi, on Jakarta's eastern border, to its west, Widodo said in a statement.

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"The first line has transformed the face of Jakarta and Indonesia's transport," Widodo said, adding that the new line promised further benefits.

In May, the Japan International Co-operation Agency said it was providing a loan of 141 million yen ($998,000) for the project.

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A JICA loan also funded the first MRT link, spanning 8 km between south and central Jakarta. Work to extend it further north is expected to be completed by 2029, seven years after it began.