Germany's biggest lender Deutsche Bank said Friday it had recruited former foreign minister and Social Democratic Party (SPD) leader Sigmar Gabriel to join its supervisory board.

"With his wealth of experience, having served as environment minister, economic affairs minister and foreign minister, Sigmar Gabriel will make a unique contribution," supervisory board chief Paul Achleitner said in a statement.

For his part, Gabriel welcomed "the opportunity and the responsibility to help shape the future of the German and European economy" at Deutsche Bank.

The lender has spent years struggling to overcome the aftershocks of the financial crisis and sector-wide headwinds like the European Central Bank's negative interest rates policy.

In October, it reported losses in the first three quarters of 2019 of 3.9 billion euros ($4.3 billion), placing it on course for one of its worst annual results ever. Chief executive Christian Sewing has thrown the bank into a massive restructuring, retreating from some flagship business areas like share trading to refocus on Europe and Deutsche's corporate banking arm.

Gabriel was SPD leader from 2009 to 2017, a period that saw the once-proud centre-left force decline sharply in the polls. On Friday, just 14 percent of respondents to a survey by public broadcaster ARD said they would vote for the party in a federal election.

Since leaving politics, he has worked as a consultant as well as heading the "Atlantik-Brücke" German-US friendship organisation and holding posts at other NGOs. Gabriel already has experience of governance at a German corporate giant, holding a seat on Volkswagen's supervisory board while serving as state premier of Lower Saxony from 1999-2003.