The number of cases of law violations in airplanes is on the rise, with smoking accounting for the most violations, data showed Friday.

According to the Ministry of Land, Infrastructure and Transport, a total of 460 cases occurred on flights operated by the seven local airlines, doubling in two years.

By type, smoking took up the most with 381 cases, followed by 42 cases of affray and 15 cases of sexual harassment. They also included nine cases of threatening the safety of others under the influence of alcohol and six cases of assault.

To prevent in-flight disturbances, the government has toughened the punishment starting this year.

Those interrupting cockpit operations can face a fine of up to 50 million won or be sentenced to a prison term of up to five years.

The government also raised the minimum number of security guards per flight to two, based on international standards, officials said.

By Lee Hyun-jeong (rene@heraldcorp.com)