Train stations and bus stops in Istanbul, used by thousands of commuters a day, could be targeted by terror groups such as the so-called Islamic State (ISIS). Advice posted on the Foreign Office website yesterday said: "On 27 July there were reports of possible threats to public transport in Istanbul." The metro stations most at risk are Taksim, Osmanbey, Yenikapi and Haciosman, the statement added. It followed the leak of an internal memo from Turkish police warning of the threat. More than 2.5million Britons visit Turkey every year – but the Foreign Office has now advised against all but essential travel to certain regions. The warning comes after Turkish police detained 1,000 people detained in a crackdown on militant groups including ISIS and the ultra-left Kurdistan Workers Party (PKK) and DHKP-C. Up to 60 foreigners were among those detained by terror police, who have carried out a series of raids in the past few days, according to Ahmet Davutoglu. The first raids took place on Friday morning, with 5,000 armed police and special forces agents storming more than 100 addresses across the country. Some took place on coastal resorts popular with British holidaymakers, such as the western town of Izmir, close to Bodrum and the Greek islands. Their fightback against ISIS began after the barbaric group claimed responsibility for a bomb attack in the Turkish town of Suruc that killed 32 people. Kurdish groups held the Turkish government responsible for the blast, saying it had not been aggressive in battling the so-called caliphate. The country has also opened up its bases to warplanes and attacked Kurdish militants in northern Iraq – leading to worries that ISIS will retaliate. Three Turkish policeman were killed in violent clashes last week - with the PKK claiming responsibility for two of the deaths. The PKK has been fighting Turkey for autonomy since 1984 and is considered a terrorist organisation by the country's government and its allies. Following the recent attacks, the Foreign Office has warned tourists: "There's a high threat from terrorism in Turkey. "There are active terrorist groups throughout the country. "These include domestic religious extremist and ideological groups, and international groups involved in the conflict in Syria. "Attacks could be indiscriminate and could affect places visited by foreigners." Holidaymakers have also been told to stay away from the Syrian border.
UK 's Foreign Office is warning UK nationals of potential terrorist attacks against tourist sites in Turkey , and yesterday cited reports of potential attacks against transport infrastructure in Turkey . This increased level of warning comes on the back of the detention of over thousands individuals by Greek security forces over yesterday .