JAKARTA (REUTERS) - Indonesian authorities have drafted in more doctors and nurses to two areas on the islands of Java and Madura after hospitals there approached full capacity amid a spike in coronavirus cases, the country's health minister said on Monday (June 7).

Health experts and officials are worried about the risk of a broader spike in virus cases fuelled by variants and a jump in travel last month as many in the world's biggest Muslim-majority country travelled back to hometowns for holidays after Ramadan.

In the district of Kudus in Java and Bangkalan on the neighbouring island of Madura, hospital capacity had hit at least 90 per cent, according to media reports.

"There are regions or clusters that are experiencing a high surge," Health Minister Budi Gunadi Sadikin told a news conference, noting that along with medical reinforcements, some patients had been moved to other cities for treatment.

In Kudus, about 300 healthcare workers had contracted the respiratory disease, local media reported. Health officials in the areas were not immediately available for comment.

Meanwhile in Bandung, the capital of the country's most populated province of West Java, hospital capacity was at 79 per cent, said Ms Ahyani Raksanagara, the head of the city's health agency.

Of Indonesia's 72,000 isolation beds, 31,000 were currently occupied, up from 22,000 people last month, said Mr Budi.

"We at the health ministry are preparing for the worst that all patients must be admitted to hospitals," said the minister.

Speaking at the same news conference, national police chief Listyo Sigit Prabowo said movement restrictions had been tightened in Kudus and Bangkalan.

Among the worst hit countries in Asia, Indonesia has reported about 1.86 million Covid-19 cases and over 51,000 deaths, with Monday's 6,993 infections the highest daily increase since March 4.

While Indonesia has not so far seen the type of sharp spike in national infection numbers that have recently prompted lockdowns in neighbours like Malaysia, some medical experts warn that far stricter controls are urgently needed.

"We're just waiting for it to explode. Kudus and Bangkalan have exploded," said University of Indonesia epidemiologist Tri Yunis Miko Wahyono.