Middle and high school students in Tokyo have been spreading the word among their friends about a new way to steal canned drinks from vending machines, it has been learned.

The Yomiuri Shimbun has learned that 33 minors, mostly middle or high school students, were questioned by the Metropolitan Police Department on suspicion of vending machine theft over a two-year period ending at the beginning of this year.

The thieves pried open the front panels of the machine to remove remote-control devices that operate them, the sources said. However, no cash was stolen in any of the cases.

According to police investigation sources, the new method was utilized in 31 cases of vending machine theft in Tokyo's Shinagawa, Ota, Itabashi and Kita wards, as well as the three western Tokyo cities of Fuchu, Chofu and Hachioji from June 2011 to last October.

Alarmed, an organisation of vending machine operators has embarked on countermeasures to prevent such thefts.

Of the 33 minors questioned by the MPD in 18 cases, 19 were middle school students and 10 were high school students.

Most have been arrested or taken into custody by the MPD.

One group comprising 10 boys and girls--most of them middle school students--in Fuchu were bought in for police questioning after allegedly stealing 141 canned beverages in one go by rigging a vending machine in a park they frequented, according to the sources.

After drinking some of the beverages, they decided to fool around by crushing the cans on the ground, they said.

In Ota Ward, a group of five high school students were questioned by police on suspicion of stealing 59 canned beverages from a parking lot vending machine, according to the sources.

In a separate incident from the 18 cases, four middle school students in Kita Ward were taken in for questioning on a voluntary basis in connection with the theft of 65 canned beverages in September 2012. The students admitted their involvement in the case, they said.

During questioning, some students were quoted as telling investigators older classmates had taught them to juggle vending machines, a popular trick among their classmates.

Others said they had sought out easily rigged vending machines so they could grab a drink whenever they felt like it.

A senior MPD officer said the new rigging method seems to have spread by word of mouth.

Damages from each case of theft is considered to be relatively minor, ranging from several thousand to several tens of thousands of yen, the officer said. Additionally, quite a few cases may have gone unreported because of negligible damage, the sources said.