Turkey summoned the Swiss envoy on Monday to complain about a decision by Swiss officials to launch initial checks to see whether Turkey's EU minister had breached the law by denying the Armenian genocide, a Turkish Foreign Ministry official said.
"This is not acceptable. The envoy has been summoned for an explanation," the official told Reuters.
According to media reports, Turkey's EU Minister Egemen Bagis said late last month at the World Economic Forum in Davos and also at a concert in Zurich that the killing of Armenians by Ottoman Turks nearly a century ago was not a genocide.
Swiss anti racism laws make it illegal to deny a genocide.
An attorney for the Zurich state prosecutor's office said Swiss officials had started an initial probe after the Switzerland-Armenia group had notified Swiss authorities about the minister's remarks.