The United States has issued a new warning to its citizens about "credible indications" of terrorist threats at tourist areas in Turkey.

In a warning posted on its website late Tuesday, the U.S. Embassy said Washington continued to receive reports that terrorist groups "are seeking opportunities to attack popular tourist destinations throughout Turkey."

Turkey has been hit by six deadly suicide bombings since July that were either claimed by Kurdish militants or blamed on the Islamic State group. Two Israeli-Americans, an Israeli and an Iranian were killed in an IS attack at Istanbul's main pedestrian street last Month. In January, 12 German tourists were killed in the city's historic district.

The U.S. Embassy asked its citizens to be vigilant in "crowded public areas and popular tourist destinations."