Indonesia's capital Jakarta plans to re-impose a partial lockdown as early as Monday over fears that surging coronavirus cases could "collapse" its under-pressure hospitals, the sprawling city's governor said.

The megacity of some 30 million will see many office buildings and large mosques closed along with restaurants and other entertainment venues, while public transport hours will also be restricted.

The announcement comes three months after an earlier lockdown was lifted, sending infection rates soaring.

"The Jakarta administration has decided to pull the emergency brake and go back to large-scale restrictions," governor Anies Baswedan said late Wednesday.

Without fresh moves to contain virus cases, the capital's hospitals could be overrun as early as next week, he said. "After that, Jakarta's health facilities would collapse," he added.

More than 100 frontline doctors in Indonesia have died of Covid-19, including 15 in Jakarta. "That adds to concerns that our health system will collapse if there are no serious measures to control the pandemic," said Halik Malik, spokesman for the Indonesian Doctors Association.

"We can't ignore or abandon patients just because health facilities and their employees can no longer accommodate them," he added.

Indonesia's main stock index tumbled five percent after the announcement on concerns about Southeast Asia's biggest economy.

Jakarta had by Thursday recorded more than 50,000 confirmed cases -- around a quarter of the national total -- as well as more than 1,350 deaths.

But with some of the world's lowest testing rates, the spread of the disease is widely believed to be much greater than official figures suggest.