German Vice Chancellor Sigmar Gabriel urged Iran at the start of a three-day visit to improve its relationship with Israel if it wanted to establish closer economic ties with Germany and other western powers.

Gabriel, who is also economy minister, is the first senior figure from a large western government to visit Iran since it struck a landmark agreement with world powers on its nuclear program last week.

The deal was reached despite strong opposition from Israel, with which Germany has cultivated a close relationship since the end of World War Two, when the Nazis killed six million Jews.

That puts Germany in a delicate position as it seeks to win new business in Iran after a 12-year standoff over Iran’s nuclear program during which sanctions sharply reduced trade and investment.

Conscious of that diplomatic difficulty, Gabriel kicked off his trip with a plea for Iran to improve relations with arch-enemy Israel and said Germany would like to act as a mediator.

“You can’t have a good economic relationship with Germany in the long-term if we don’t discuss such issues too and try to move them along,” Gabriel told a gathering of German and Iranian business people in Tehran.

“Questioning this state’s (Israel’s) right to existence is something that we Germans cannot accept,” he said, adding that now Berlin and Tehran can re-establish closer ties it was necessary to talk about human rights.

Gabriel, who will hold talks with Iranian President Hassan Rohani and several ministers, said he wanted to talk to human rights representatives in a country that the United Nations says is guilty of human rights violations against women, religious minorities, journalists and activists.

– Read more: Germany: Economic Ties with Iran Depend on Improving Relations with Israel – Haaretz