BERLIN (AP) — Britain’s top diplomat is demanding that Germany relax its ban on arms sales to Saudi Arabia because they are affecting UK sales of weapons to the oil-rich kingdom.

German weekly Der Spiegel reported Wednesday that British Foreign Minister Jeremy Hunt sent a blistering letter to his counterpart in Berlin earlier this month, warning that Germany’s credibility as a partner is at stake over its restrictions on arms exports to the Gulf nation.

The export ban means Britain can’t ship war planes such as the Typhoon to Saudi Arabia because they contain German-made components.

Asked about the letter after a speech in Berlin, Hunt said the “strategic relationship that the UK has with Saudi Arabia is what allows us to have a huge influence in bringing about peace in Yemen.”