SEOUL - Education-obsessed South Korea rescheduled rush hour and airline flights Thursday as hundreds of thousands of schoolchildren sat a college entrance examination seen as crucial to their future.

Government offices nationwide opened one hour later than normal and private firms were advised to do likewise to reduce traffic congestion, as students headed to 1,124 centres to sit the College Scholastic Aptitude Test.

Flight takeoffs and landings were to be banned for two separate periods totalling about 30 minutes when students take oral examinations as part of the overall test.

The Korea Airports Corp said 94 domestic flights would be rescheduled or cancelled, and two international flights were also expected to be re-timed. Cars were banned from sounding their horns near test centres during the same periods.

Even the stock and foreign exchange markets opened one hour later than usual.

Extra bus and subway services were laid on to get students to centres on time for the day-long exam, an annual ritual in a country where entry to a prestigious university is seen as the key to lifetime success.

Swine flu was an added complication this year. Examinees who have either tested positive for the (A)H1N1 virus or are suspected of being infected will take the test in separate rooms.

Electronic devices including mobile phones were banned to avoid hi-tech cheating.

Critics say the test assesses rote learning at the expense of creativity, and encourages expensive private tutoring to supplement the state education system.

After the official school day ends, many parents force young children to study until late in the evening at cram schools, with the aim of getting a head start in the college test.

An estimated 200 stressed students commit suicide every year, according to police statistics.

Central bank figures show household spending on private education rose to 20.9 trillion won (S$25.08 billion dollars) in 2008 from 20.04 trillion (S$24.05 billion) won a year earlier, despite the economic slowdown.

President Lee Myung-Bak's government is pushing for curbs on the cram schools, which are blamed for driving poor households into debt as well as stressing out young children.

A reform package announced earlier this year includes measures to normalise public education and to limit the opening hours of the private cram schools.