JAKARTA: Indonesia has delayed until next month a free trial launch of its $7.3 billion high-speed rail line, the consortium behind it said on Tuesday, the latest in a series of setbacks for the flagship, China-funded project.

PT KCIC, a consortium of Indonesian and Chinese state companies behind the 142-kilometre (88-mile) railway connecting the Indonesian capital Jakarta and Bandung city, said more time was needed to ensure passengers' safety and comfort.

The project, which is part of China's Belt and Road Initiative, was originally set to be completed by 2019 but has been beset by problems, including a $1.2 billion cost overrun and delays on its commercial operation.

A free, limited trial run for passengers, initially set for Aug. 18, has been postponed to early September, but no delay is expected to the full operational launch on Oct. 1, KCIC said on Tuesday.

Safety checks were ongoing as of last Friday, according to transport ministry official Mohamad Risal Wasal.

KCIC said internal trials had gone smoothly but the company was still working with the transport ministry on necessary operational certificates.

Chinese President Xi Jinping told President Joko Widodo during the Indonesian leader's trip to China last month that both countries must ensure the project adheres to high standards as it nears completion. (Reporting by Stefanno Sulaiman; Editing by Gayatri Suroyo, Kanupriya Kapoor)