Coronavirus-hit Indonesia received desperately needed supplies of oxygen and protective equipment from neighbouring Singapore Friday to support its overwhelmed healthcare system, as restrictions were tightened in several cities. 

The Southeast Asian archipelago is facing its most serious outbreak yet, driven by the highly infectious Delta variant, reporting hundreds of deaths and tens of thousands of cases daily.

Hospitals are struggling to cope, with many now refusing new patients, leaving scores to die at home, while desperate relatives hunt for oxygen tanks to treat the sick.

Singapore sent supplies including oxygen cylinders, ventilators, masks, gloves and gowns on two air force planes to Jakarta, the city-state's foreign ministry said. 

Another 1,000 ventilators were due to arrive from Australia Friday, while Indonesian officials plan to buy more supplies of oxygen and other equipment.

The supplies are sorely needed as hospitals set up makeshift treatment tents in parking lots and doctors and other medical workers increasingly become infected.

Nearly 1,000 Indonesian medical workers have died of Covid-19, including more than a dozen who were already fully inoculated, according to the country's medical association. 

Authorities announced Friday that medics would be given a third booster jab using the vaccine made by US company Moderna, in an effort to provide them extra protection. 

Indonesia has relied heavily on Sinovac in its vaccine rollout so far, but the medics' deaths have raised fresh concerns about the Chinese-made jab.

At a hospital in Surabaya, on hard-hit Java island, virus patients were queuing for treatment as the facility struggled to cope with a shortage of medics. 

"Many of our own medical workers are infected by Covid-19," said hospital spokeswoman Redita Putri Iriani.

"When a patient is discharged, a new one immediately arrives. We all feel overwhelmed."

With the country's outbreak showing no signs of slowing, stricter curbs will be implemented in 15 more cities from Monday, said senior minister Airlangga Hartarto. 

The restrictions in the cities on Sumatra island, the Indonesian part of Borneo and Papua will be similar to those already implemented earlier this week on the main island of Java and holiday hotspot Bali.

Offices, mosques, parks, shopping malls and restaurants will be closed and working from home will be mandatory. Less stringent restrictions are in place across the rest of the country. 

Indonesia, with a population of 270 million, has recorded a total caseload of over 2.4 million -- but testing rates are low and experts believe the true figure is far higher.