The Department of Foreign Affairs has issued travel advice
Nine of the ten people killed in a suicide bomb attack in the Turkish city of Istanbul are German, an official has said.
The blast went off in the Sultanahmet Square, next to the city's famous Blue Mosque landmark, at 10.20am local time (8.20am Irish time), according to Turkish newspaper Hurriyet.
Deputy PM Numan Kurtulmus said the suicide bomber is a 28-year-old Syrian national. At least 15 people are reported to have been injured.
Turkey's Prime Minister told German Chancellor Angela Merkel that most of those who died were German.
Germany has warned its citizens to avoid crowded places away from tourist attractions in Istanbul, saying that further violent clashes and "terrorist attacks" are expected across Turkey.
Ms Merkel, who said that the Germans involved were from a group travelling together, said: "Today Istanbul was hit; Paris has been hit, Tunisia has been hit, Ankara has been hit before".
"International terrorism is once again showing its cruel and inhuman face today".
Turkey's Dogan news agency reported that at least six Germans and one Peruvian were among the wounded. Norway's foreign ministry confirmed that one of its citizens was injured.
The Department of Foreign Affairs is asking Irish people to exercise caution in Istanbul.
It says Irish people there should follow the instructions of security personnel.
"We strongly advise against travelling to the border areas between Turkey and Syria in light of the current instability in the region, in particular the provinces of Hatay, Kilis, Gaziantep, Sanliurfa and Mardin", it adds.
Seoul's Foreign Ministry, meanwhile, told reporters that one South Korean had a finger injury.
Police sealed off the scene, which is near an obelisk in the area that is on the site of the ancient Roman hippodrome.
No group has claimed responsibility, but Turkey has been the scene of numerous acts of terrorism in the past, including several claimed by al Qaeda-linked groups and Islamic State.
More than 30 people were killed in a suicide attack in the town of Suruc, near Turkey's border with Syria, in July - an attack claimed by IS.
NATO member Turkey has been part of the coalition fighting IS in Syria since 2014, but is also conducting military operations against Kurdish groups it regards as terrorists.
Unnamed Turkish security officials told the Reuters news agency that IS militants are suspected to have been responsible for the latest Istanbul blast.
The country's President Recep Tayyip Ergogan said that Turkey is the first target of all terrorist groups in the region, as his country is fighting them all "equally".
Natalie Carney is a journalist based in Istanbul.
She told Newstalk Lunchtime that security forces believe the attack could be associated with Islamic State.