South Korea is to track the mobile phones of hundreds of people under quarantine as part of measures to contain the spread of Middle East Respiratory Syndrome (MERS), as the country reported its fifth death from the virus.

Choi Kyung-hwan, the country's acting prime minister, held a briefing on Sunday morning and announced new measures to control the virus, as fears grew among South Koreans over the outbreak.

Choi also named 24 hospitals where the infections took place or confirmed MERS patients visited, reversing a previous policy of not naming the hospitals after public criticism.

"There are a total of 24 hospitals, where infections took place or MERS patients visited. Six hospitals among them, including Pyeongtaek St Mary's Hospital and Samsung Medical Center, are where the confirmed cases occurred. The remaining 18 are hospitals where MERS patients have visited," Choi said.

The number of infections in the country rose to 64 after 14 new cases were confirmed on Saturday night, the health ministry said.

All of the 14 new cases were among a group of 1,820 people quarantined after being exposed to those diagnosed earlier, it added.

Most of those under quarantine had been told to stay home and strictly limit their interactions with others, while some had been isolated in state hospitals.

However, Busan city authorities reported an additional case in the country's southern port and second-largest city, sparking alarm that the outbreak might have spread nationwide.

The Busan case was not included among the 14 new infections confirmed by the health ministry on Saturday.

Largest fresh outbreak

Choi vowed on Sunday that "all-out efforts" would be made to curb the spread of the disease in Asia's fourth-largest economy.

"We can absolutely control this because all MERS cases in our country are infections in health facilities, not spreading into communities," Choi said.

He urged the public not to panic, saying all patients had already been in hospital.

South Korea's outbreak of the often-deadly virus, first reported on May 20, is the largest outside the Middle East, prompting public fear and questions over the government's initial response.

First identified in humans in 2012, MERS is caused by a coronavirus from the same family as the one that triggered Severe Acute Respiratory Syndrome (SARS).

However, MERS has a much higher death rate at 38 percent, according to World Health Organization figures.

There has been no sustained human-to-human transmission, but the worst-case scenario is that the virus changes and spreads rapidly, as SARS did in 2002-2003 when it killed about 800 people around the world.

South Korea's new cases bring the total number globally to about 1,208, based on WHO data, with at least 444 related deaths.

Source: Agencies