Prosecutors in several German regions have launched probes of companies offering free Covid-19 tests after news reports said that some were padding their numbers to claim more money from the government, AFP reports.

Prosecutors raided a company in the northwestern city of Bochum, according to the Suddeutsche Zeitung newspaper, while farther north in Luebeck, prosecutors have opened a fraud probe, the WirtschaftsWoche weekly said.

In Cologne, authorities carried out a surprise control of a testing centre, and the city of Munster has revoked the license of a company that operates around 50 testing centres.

In an effort to boost Covid-19 testing, the German government made testing free several weeks ago, reimbursing companies up to 18 euros ($22) for each test conducted.