JERUSALEM (Reuters) – Israeli Prime Minister Benjamin Netanyahu on Monday threatened to cancel a meeting with Germany’s foreign minister if he sits down with a left-wing rights group, an Israeli official said.

German Foreign Minister Sigmar Gabriel was due to meet with “civil society” groups on Tuesday, said a spokeswoman in Berlin who declined to identify the groups.

Israeli media said Gabriel would meet with “Breaking the Silence,” a group that collects testimonies from Israeli veterans about the military’s treatment of Palestinians in the occupied West Bank and the influence it says Israeli settlers have on the army’s actions.

The German spokeswoman had no comment on Netanyahu’s threat to cancel his meeting with Gabriel. Officials traveling with Gabriel were not immediately available for comment.

Germany in March canceled an annual meeting of German and Israeli leaders that was to take place in May amid rising frustration in Berlin with settlement activity in the Israeli-occupied West Bank.

Gabriel is visiting the Middle East to press for a two-state solution to end the conflict between Israel and the Palestinian government.

Gabriel appealed to the Israeli government to continue to work for a pluralistic society and defy nationalism in a column to be published Tuesday, said the German newspaper Frankfurter Rundschau.

“Democracy is the most difficult and at the same time best form of government because it continues to seek common ground in a never-ending dialogue, even despite very different viewpoints and positions that run contrary to peaceful coexistence,” he wrote.

In February, Netanyahu ordered the reprimand of the Belgian ambassador after Belgian Prime Minister Charles Michel with representatives Breaking the Silence and B’tselem, another rights group, during his visit to the region.

Both organizations have become popular targets for right-wing politicians who accuse them of damaging Israel’s reputation abroad and putting Israeli soldiers and officials at risk of prosecution.

In 2016 Israel passed a law requiring non-government organizations that receive more than half their funding from foreign governments or bodies to provide details of their donations. The legislation was largely seen as targeting left-wing organizations such as B’tselem and Breaking the Silence and drew international criticism.

(Additional reporting by Andrea Shalal in Berlin, Writing by Ori Lewis; Editing by Lisa Shumaker)