Korean Coast Guard officials are investigating several Chinese tourists on suspicions of attempting to illegally enter mainland Korea without a visa on Monday, said officials.

According to the Jeju Coast Guard, six Chinese tourists entered Jeju Island and attempted to cross over to the mainland without visas.

As the nation’s free international city, Jeju started offering visa-free entry in 2005 and has since become a popular destination among Chinese tourists because of its close proximity.

Coast guard officials report that the group had help from a Korean, who is also in custody.

The tourists stowed away in a passenger vehicle on a ferry crossing from Jeju Island to Wando, South Jeolla Province. However, coast guard officials apprehended the group after receiving a tip-off.

According to officials the group arrived in Jeju on Sunday and asked the owner of the vehicle to help them cross over to the mainland for 2 million won ($1,776) a person.

According to government data, as of 2011 there are over 67,000 illegal Chinese immigrants in the country.

By Robert Lee(robert@heraldcorp.com)