Services at the US embassy in Turkey have been suspended after "credible reports of potential terrorist attacks", the US said on Friday. The US said the suspension included all American citizen and visa services at all missions across the country. The embassy said in a security alert on its website that it "has received credible reports of potential terrorist attacks and kidnappings against US citizens and foreign nationals in Istanbul, including against the US consulate general, as well as potentially other locations in Turkey".<br/> The report advised US citizens to exercise heightened caution in locations where people may gather, including large office buildings or shopping malls. Diplomatic staff in Ankara said that consular services would be suspended at the embassy, as well as at consulates in Istanbul, the southern city of Adana and the Aegean coastal city of Izmir. Turkey has experienced a period of calm after a series of terrorist attacks from groups including Islamic militants and Kurdish separatists. In 2013, a suicide bomber blew himself up at the US embassy in Ankara, killing himself and a Turkish security guard. A far-left radical group claimed responsibility for the attack. In 2016, the US government ordered all civilian relatives of its Istanbul consulate staff to leave Turkey because of increasing threats from terrorist groups. Turkey was hit by a string of attacks in 2015 and 2016 by several groups, including ISIS.