ISIS has claimed responsibility for the attack on a nightclub in Istanbul that killed 39 people on New Year`s Eve.The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group put out a statement claiming responsibility for the raid on Monday."In continuation of the blessed operations that Islamic State is conducting against the protector of the cross, Turkey, a heroic soldier of the caliphate struck one of the most famous nightclubs where the Christians celebrate their apostate holiday," the statement said.The announcement came as a manhunt was under way in Turkey for at least one assailant who attacked those celebrating New Year at the Reina nightclub.The Reina lies on the shore of the Bosphorus Strait and is one of Istanbul`s best-known nightclubs, popular with locals and tourists alike. During the attack, some partygoers who managed to flee jumped into the freezing cold Bosphorus strait to escape harm.As well as the 39 dead, about 70 others were wounded and three of those people remain in critical condition, Binali Yildirim, Turkey`s prime minister, said on Sunday.Interior Minister Suleyman Soylu described the attack as a "massacre, a truly inhumane savagery".Foreigners including many nationals of Arab countries were among the dead, officials said.Eleven of the dead were Turkish nationals and one was a Turkish-Belgium dual-national, they said.Seven victims were from Saudi Arabia and had travelled to Istanbul for New Year`s Eve celebrations.Three of the dead were from Lebanon and Iraq each.Two nationals from Tunisia, India, Morocco and Jordan were killed, and Kuwait, Canada, Israel, Syria and Russia lost one citizen in the attack.One victim remains unidentified.Security measures had been heightened in major Turkish cities, with police barring traffic leading up to key squares in Istanbul and Ankara.In Istanbul, 17,000 police officers were put on duty, some disguised as Santa Claus and others as street vendors, Turkey`s Anadolu news agency reported.Turkey, part of the US-led coalition against ISIL, faces multiple security threats including fallout from the war in neighbouring Syria.It has seen repeated attacks and bombings blamed on ISIL as well as fighters from the Kurdistan Workers` Party (PKK) in recent months.Source: News agencies