BERLIN (Reuters) - German politicians on Wednesday criticized Chancellor Angela Merkel for saying that people with a Turkish background who live in Germany should show "loyalty to our country", calling her comment unnecessarily divisive at a particularly difficult time.

Adding to mounting strains on relations between Germany and Turkey, a major partner in regional attempts to stem mass migration, a leaked government report last Wednesday alleged that Turkey was a hub for Islamist groups.

German media have also reported that the Turkish government's MIT intelligence service had a network of 6,000 informants in Germany.

In an interview published on Tuesday, Merkel had told the Passauer Neuen Presse newspaper: "We expect those with a Turkish background who have lived in Germany for a long time to develop a high degree of loyalty to our country."

In exchange, she said, Germany was trying to be open to their concerns and to understand them.

German integration commissioner Aydan Ozugus, a member of the Social Democrats that rule in coalition with Merkel's conservative Christian Democrats, criticized her comments in an interview with newspaper chain Funke Mediengruppe.

She said a clear majority of those with a Turkish background "felt allegiance to our country" and should not be assumed to have conflicting loyalties.

Volker Beck, migration spokesman for the Green party, told the Handelsblatt newspaper: "Questioning the loyalty of your own citizens without any particular reason is a practice that we generally see only in authoritarian regimes."

He said people with a Turkish background needed to support German values such as human dignity and human rights, regardless of language, religion and ethnic origin, not declare "loyalty" to one country.

Tensions are already high in the 3-million strong Turkish community in Germany between supporters of Turkish President Tayyip Erdogan and those of a U.S.-based cleric he blames for a thwarted coup on July 15.

Erdogan backers have demonstrated in several German cities since the attempted coup, shops have been boycotted by rival sides and hate mail has been sent to anti-Erdogan politicians.

(Reporting by Andrea Shalal; Editing by Louise Ireland)