SEOUL - SOUTH Korea has quarantined a 25-strong group of high-school students and teachers from Hawaii, with five of them already having tested positive for swine flu, authorities said on Wednesday.

The 21 students and four teachers have been in a quarantine hospital near Seoul since they arrived on Monday, the health ministry said.

'They have been in quarantine for treatment and observation,' a ministry official told AFP on condition of anonymity.

'The five students displayed symptoms even before they got on the plane and they reported to airport quarantine authorities when they landed,' she said.

It usually takes a week for travellers to be released from quarantine, she added.

Including the five students the ministry on Wednesday confirmed seven additional cases of (A)H1N1 flu, bringing the number of infections here to 128.

No one has died.

Earlier this month South Korea ordered an Australian lacrosse team to stay in a hotel for five days after one of the team was diagnosed with swine flu.

A(H1N1), which emerged in Mexico in April, has been declared a pandemic by the World Health Organization. It has killed 231 people worldwide and infected more than 52,000 people in 100 countries. -- AFP