Berlin  - German Foreign Minister Frank-Walter Steinmeier suggested in a parliamentary debate Friday that the United States should remove its arsenal of nuclear weapons from German soil.

"If we wish Europe to be made into a nuclear-free zone, that would also apply to the nuclear weapons still left in Germany," he told the Bundestag lower chamber in Berlin during a debate on disarmament.

Steinmeier is leading the campaign by Germany's Social Democratic Party (SPD) to unseat Chancellor Angela Merkel in this September's general election. The SPD currently rules Germany in coalition with Merkel's Christian Democratic Union (CDU).

There are no officially confirmed numbers on how many US nuclear weapons are stockpiled at US bases on German soil, but academics have estimated the total at 20.

Steinmeier reiterated his backing for a call by US President Barack Obama to rid the world of nuclear weapons, but added that doing so would "not be easy" and would require much patience. (dpa)