The elections under way on Sunday showed an intense wave of votes for the Sweden Democratic Party, who are known for their anti-immigration goals.

Experts expect the US president to use the occasion to mobilize international support for renewed economic sanctions.

Those detained were among 89 people whose detention was ordered in an investigation by Istanbul prosecutors, 'Hurriyet' newspaper reported.

Senior diplomat Saeb Erekat said that the American move would not deter Palestinian legal action against Israel.

"We reiterate that the rights of the Palestinian people are not for sale, that we will not succumb to US threats and bullying," Erekat said in a statement.

The U.N. Office for the Coordination of Humanitarian Affairs said an all-out military assault on the last major stronghold of active opposition to President Bashar Assad could set 800,000 to flight.

Overseas military action remains a sensitive and deeply unpopular topic in Germany, given its Nazi past.

Sweden saw itself as a "humanitarian superpower" for years, but a rise in gang violence in areas of high unemployment has won support for the far-right Sweden Democrats.