Authorities in five European countries said Thursday they had staged a coordinated swoop on suspected users of spy malware that gives remote access to other people's smartphones.

The illegal software in question, DroidJack, allows cybercriminals to hijack Android smartphones and snoop on data traffic, listen in on conversations, use the camera and send text messages without the owner knowing.

Prosecutors in the western city of Frankfurt confirmed Germany initiated the European crackdown, which also included raids on Tuesday in Britain, France, Belgium and Switzerland coordinated by Europol, the EU's law enforcement agency, and Eurojust, its judicial network.

The German searches, which were carried out across six states, targeted people who had bought DroidJack and used it in 2014 and 2015.

The suspects ranged in age from 19 to 51 and had no links among them, a spokesman for the Frankfurt prosecutor's office, which specialises in cybercrime, told AFP without providing further details.

In France, four people of diverse backgrounds and ages were questioned by police on suspicion of buying the software and later released, a police source said.

A spokeswoman for Switzerland's federal police said one search was carried out, with no arrests.

The sales director of cybersecurity company Lexsi, Jerome Robert, described DroidJack as a so-called remote administration tool that had gained in popularity over the last year.

It can be physically installed on any Android smartphone, or unwittingly downloaded via phishing.

"We have seen it in a few cases of banking cybercrime but it still remains far behind the usual means of cybercrime for PCs (in frequency of use)," Robert said.