Following cyberattacks on water supply systems in the US state of Minnesota, similar disruptions have also become public in Michigan.

"We have received a few reports from communities in Michigan that showed activities consistent with the descriptions from the federal authorities," a spokesman for the state's environment department told dpa on Saturday.

He stressed that all systems continued to operate safely and that the "issues" had been resolved by local operators. "No impacts are known that would pose a risk to public health," he added.

The Federal Bureau of Investigations (FBI) previously said a number of US states had contacted the agency.

"Since 27 July 2026, Water and Wastewater Sector (WWS) utility companies in at least seven states have reported incidents to the FBI, and some of that activity degraded water operations," the agency said in a statement.

"After remotely accessing internet-facing devices, the actors changed the IP addresses and passwords, resulting in a loss of monitoring and control functionality," the FBI said. It did not say whether Iran was behind the attacks.

The US Cybersecurity and Infrastructure Security Agency (CISA) meanwhile warned of cyberattacks carried out by individuals linked to Iran. These target government services and facilities, water and wastewater systems and the energy sector.

According to media reports, there were also attacks this week in the state of Minnesota on dozens of water supply systems. At least one system was temporarily taken offline as a result. Experts suspect Iranian hackers are behind it. The Washington Post reported that intelligence agencies assumed this, while the New York Times cited investigators.

Both newspapers relied on US officials and each noted that the findings were not yet final. US President Donald Trump, by contrast, suggested it was not Iran but what he called the incompetent Minnesota Democratic Governor Tim Walz who was behind it.

Top Democratic politicians in the state told US media that Trump's allegations are baseless.

Walz, in a post on X, wrote: "Trump knows exactly who is responsible for this attack, and knows that other states were hit too.

"This is what modern warfare looks like, and it further illustrates there's no plan to win a war with Iran."