TOKYO (Kyodo) -- A revised Japanese traffic law took effect Friday, introducing prison terms and fines for cyclists who use their mobile phone or ride while under the influence of alcohol.

People caught using their phone -- for calls, texts or just looking at it -- face imprisonment of up to six months or a fine of up to 100,000 yen ($650). If they cause an accident, they face a prison term of up to one year or a fine of up to 300,000 yen.

Previously, mobile phone use while cycling was punished according to rules set by local public safety commissions, with offenders facing a fine of up to 50,000 yen.

The revised Road Traffic Act also strengthened penalties for people who cycle under the influence of alcohol. Riders found with more than 0.15 milligram of alcohol per liter of breath face a prison term of up to three years or a fine of up to 500,000 yen.

The more serious offence of cycling while drunk was already included in the current law. Offenders face a prison term of up to five years or a fine of up to 1 million yen.

Shortly after the law took effect, the Osaka prefectural police said Friday they had already issued a red ticket to a cyclist under the influence of alcohol and are investigating six other cases.

There were 295 accidents caused by cyclists using mobile phones between 2013 and 2017, but the number of cases increased by more than 50 percent to 454 in the following five-year period, the National Police Agency said.

An agency official said the rise could be attributable not only to the prevalence of smartphones but the growing variety of video and game content available on them.