More than 60 security cameras made by Canon Inc. have been hacked and rendered unusable at places including key waterways, a fish market and a care facility for people with disabilities, it was learned Monday.

Many of the networked cameras had messages left on their screens saying, “I’m Hacked. bye2.”

Although it is unclear why those particular cameras were targeted, two cities — Yachiyo in Chiba Prefecture and Ageo in Saitama — that lost control of waterway cameras noted they had not reset the default password.

Canon said it could not comment on each individual case but urged clients on its website to change the default password.

Security cameras connected to the internet allow monitoring by computers, smartphones and other mobile devices via “internet of things” technology. But experts say such cameras can be used as an entry point for hacking the computer systems of governments and companies as well.

“The cases indicate (internet of things technology) has many security issues,” an information security expert known by the alias “piyokango” said. “It is important that you make sure to change the default passwords.”

Hacked cameras were reported at several locations, including a fish market in Hiroshima, a care facility in Kobe and the branch of a Saitama-based firm in Naha, Okinawa Prefecture.

The fish wholesaler in Hiroshima said its security cameras suddenly went black late last month.

Yachiyo officials noticed the problem on April 24 and determined that the camera’s password had been changed. They later removed the camera from the network and reported the incident to the police.

Ageo discovered its hacking problem on April 26, prompting an official to admit the city had failed to take precautions.

“We had not predicted this kind of situation,” the official said.

Some Japanese companies and government bodies are said to be inordinately susceptible to hackers.

It was only in January that Coincheck, a major cryptocurrency exchange, was hit by the largest theft of digital currency ever recorded.

During a visit to the Middle East earlier this month, Prime Minister Shinzo Abe asked Israel, a country known for its digital prowess, for cybersecurity cooperation.

Japan hopes to bolster its cybersecurity capabilities in the run-up to the 2020 Tokyo Olympics and Paralympics.