Germany's foreign minister has tried to reach out to the country's Turkish-rooted citizens, saying the crisis between both countries isn't directed against them.

Sigmar Gabriel wrote an open letter to the 3.5 million Germans of Turkish descent, which was published in both Turkish and German in Bild daily paper Saturday. He said that the government wants to let them know that "the friendship between Germans and Turks is a great treasure."

More than a year of strains in the countries' relationship came to a head this week with Turkey's jailing of a German human rights activist who had no previous links to Turkey, but was accused of links to terror groups. Germany reacted Thursday by publishing a new travel advice asking Germans to exercise caution when traveling to Turkey.