The German Foreign Ministry has confirmed that eight of the dead were German citizens.
The Turkish government had already confirmed that most of the people who died in the attacks were German.
Chancellor Angela Merkel said earlier on Tuesday it was likely that Germans had died in the terrorist attack which hit Istanbul earlier in the day.
"We're deeply worried that Germans are among the victims and the injured - we believe this to be probable," Merkel said after a meeting with Algerian prime minister Abdelmalek Sellal in Berlin.
Blast hit world-famous tourist site
Initial reports from city authorities in Istanbul said that 10 people had been killed and 15 injured in the blast in the Sultanahmet area of the city, one of the busiest destinations for tourists thanks to its many mosques and other cultural sites.
#BREAKING Ten killed, 15 wounded in Istanbul blast: local authorities- AFP news agency (@AFP) January 12, 2016
Turkish journalists tweeted soon after the blasts that Germans were among the victims, although there were no figures available immediately.
An official for a tour company told Reuters that a group of German visitors were in the area at the time of the blast and Turkish media were quick to report German casulties.
German tourists among the dead in Istanbul blast https://t.co/0Q5BVbT6td- Kadri Gürsel (@KadriGursel) January 12, 2016
Turkish President Recep Tayyip Erdoğan said that the attack had been a suicide bombing carried out by a terrorist of Syrian origin.
#BREAKING Erdogan says Istanbul attack caused by suicide bomber of Syrian origin- AFP news agency (@AFP) January 12, 2016
The blast was large enough to be heard up to a mile away.
I heard loud crash outside my window in Cukurcuma, about a mile away- thought it was something falling due to the strong winds #Sultanahmet- Alex Christie-Miller (@AChristieMiller) January 12, 2016
Turkish Prime Minister Ahmet Davutoğlu called an emergency meeting of security officials and ministers to respond to the attacks.
The German Foreign Ministry Twitter account warned tourists in Turkey to "avoid large gatherings for the time being".
In more detailed advice on its website, the Ministry suggested that tourists avoid "gatherings in public spaces and in front of tourist attractions".
"Across the country, continued political tensions and violent confrontations can be expected," the official advice continued.
"Germans staying in Germany or who want to travel there are recommended to keep informed of the security situation in real time using this travel and security advice page and media reports."