Israel's prime minister has made his first comments on a brewing scandal over the purchase of German submarines, saying his only consideration was fortifying the country's security.

Benjamin Netanyahu's comments Sunday come amid calls for an inquiry after it was revealed his personal attorney, David Shimron, had represented the German company building the submarines. The reports into Shimron's involvement in the sale raised concerns over a potential conflict of interests. Suspicions of impropriety were heightened after former Defense Minister Moshe Yaalon said he was sidelined on the plans.

Israel has ordered six submarines from Germany over the past two decades. Israel decided to buy three new ones to replace its older submarines.

Netanyahu says the purchase is essential to Israel's security and that was "the only consideration that guided me."