SEOUL, Feb 5, 2008 (AFP) - Millions of South Koreans took to the roads Tuesday, jamming routes nationwide, on the eve of the country's most important holiday marking Lunar New Year.

The transport ministry expects more than 40 million of the nation's 49 million people will this week make journeys of some sort for family reunions or traditional ancestral rites.

The Korea Highway Corporation predicts 2.15 million cars will leave Seoul this week, jamming expressways and doubling or tripling journey times between the capital and other parts of the country.

"Most highways are already jammed. We expect some 380,000 cars to exit the capital today," corporation spokesman Bong Yong-Chae told AFP.

The three-day holiday, starting Wednesday this year, is one of the country's two biggest festivals along with the Chuseok or thanksgiving holiday in autumn.

As in China, families gather to pay respects to ancestors and visit relatives and friends on Lunar New Year's Day, which falls on Thursday.

More and more people are, however, using the break to visit resorts or go abroad.

Hotels and condominiums at South Korean ski resorts are fully booked. And airport officials have forecast that more than 300,000 people will fly abroad this week, including 130,000 during the three-day holiday.

"The number of Lunar New Year travellers has been on the rise every year. This year we expect the biggest number of people to travel," said transportation ministry official Im Keun-Yul.

More than 40 million people would be on the move in buses, taxis, cars or trains, Im forecast.

The ministry has increased frequencies of trains, buses, planes and ferries. More than 500 temporary toilets have been set up along jammed roads. Health authorities have prepared guidelines for emergency treatment during the holiday.

Relatives separated by the world's last Cold War frontier will gather near the border for annual events publicising their plight.

North Korea has officially observed the Lunar New Year since 2003 following instructions from leader Kim Jong-Il. This year it comes ahead of his 66th birthday on February 16, which is also a public holiday.

One South Korean district, which was hit by the nation's worst oil spill in early December, is facing a grim holiday.

Scores of marine farms and kilometres (miles) of beaches in and around Taean county on the Yellow Sea coast were fouled by the leak from a holed supertanker.

A huge clean-up by hundreds of thousands of volunteers and others has been under way. But tourists who used to visit the district, even in winter, are still staying away.