PKK-affiliate, TAK, says it carried out the attacks at the Vodafone Arena in Istanbul on Saturday evening, killing 38 police and 8 civilians.
Turkey's Health Minister, Recep Akdag, on Monday said the death toll from Saturday's terrorist attack in Istanbul had risen to 44, 38 police and 8 civilians.
The PKK-affiliated TAK terrorist group on Sunday claimed responsibility for two bomb blasts outside the Vodafone Arena in Istanbul's Besiktas District on Saturday night that killed at least 44 people, and injured over 150. The first was a car bomb outside the stadium, followed within a minute by a suicide bomb attack in an adjacent park.
The group made the claim in a statement on its website. TAK has also claimed responsibility for a number of other attacks in Turkey this year, including two bombings in Ankara in February and March which combined killed at least 67 people.
President Recep Tayyip Erdogan condemned Saturday's attacks, saying those responsible would pay.
"What we must focus on is this terror burden. Our people should have no doubt we will continue our battle against terror until the end," Erdogan said after meeting injured victims in an Istanbul hospital. Erdogan also cancelled a scheduled state visit to Kazakhstan.
Deputy Prime Minister Numan Kurtulmus pointed to PKK involvement.
"Indicators point to the PKK. It clearly was a planned event. Once the investigation is done, the findings will be announced. We cannot say anything definite for now."
Turkish news outlet Anadolu Agency on Monday said police have detained 118 people in raids across Turkey, targeting officials from the Peoples' Democratic Party (HDP) over allegations of links to the PKK.
The operation was launched after TAK claimed responsibility for Saturday's attacks.
The Istanbul attacks were two of several in Turkey this year. Authorities suspect that the perpetrators targeted a police bus.
Interior Minister Suleyman Soylu described the blasts outside the stadium, where two of the nation's top football teams squared off earlier in the evening, as "cruel and heinous."
One hundred and fifty-five people are being treated in hospital, with 14 of them in intensive care and five in surgery, Health Minister Recep Akdag told a news conference.
Sunday was declared a day of mourning in Turkey. Flags flew at half mast in honour of the victims.
World leaders used social media to express solidarity with Turkey and its people following the blasts.
In Washington, the White House condemned the attack and pledged solidarity.
"Our thoughts and prayers go out to the victims, their families and loved ones, and to all the people of Turkey," National Security Council spokesman Ned Price said in a statement.
The president of the European Parliament, Martin Schulz, said on social media, "My thoughts & solidarity with Turkish citizens, with families of victims of Istanbul attack. I wish speedy and full recovery to the injured."
My thoughts & solidarity with Turkish citizens, with families of victims of #Istanbul attack. I wish speedy and full recovery to the injured— Ex EP President (@EP_PresSchulz) December 10, 2016
A spokesman for the secretary general of the Council of Europe, Daniel Holtgen, said Ankara can count on Europe's support.
"Turkey can rely on the solidarity and support of European governments and the Council of Europe after today's Istanbul terrorist attack," he added.
NATO Secretary General Jens Stoltenberg described the attacks as "horrific acts of terror." He said that NATO stands united in solidarity with its ally Turkey and that "we remain determined to fight terrorism in all its forms."
I condemn the horrific acts of terror in #Istanbul. My thoughts are with those who lost their loved ones and our Ally Turkey.— Jens Stoltenberg (@jensstoltenberg) December 10, 2016
UK Secretary of State and Commonwealth Affairs, Boris Johnson tweeted "UK committed to working with Turkey to tackle terrorism," and that his thoughts are with all those affected.