Police detained Hilmi Aydogdu, leader of the Democratic Society Party's branch in the mainly Kurdish city of Diyarbakir, as he left a conference and questioned him over the remarks, said Nazmi Gur, a party spokesman.
Prosecutors later formally arrested Aydogdu and charged him with threatening public safety by inciting racial enmity and hatred. The charge carries a maximum three-year prison sentence.
In remarks published in several newspapers, Aydogdu had warned Turkey against taking any action in the oil-rich Iraqi city of Kirkuk.
Turkey, which has been trying to quell a domestic Kurdish insurgency for more than two decades, fears that Iraqi Kurdish groups could seize control of the northern city and incorporate it into their self-ruled region.
Some in Turkey have suggested that Ankara could take military action to prevent that from happening.
"The two sides in this war would be Turkey and the Kurds in Iraq. There are some 20 million Kurds in Turkey, and the 20 million Kurds would regard such a war as an attack against them,' newspapers quoted Aydogdu as saying.
"Any attack on Kirkuk would be considered an attack on Diyarbakir,' the politician was also quoted as saying.
Turkish leaders are concerned that Iraq's Kurds want Kirkuk's oil revenues to fund a bid for independence that could encourage separatist Kurdish guerrillas in Turkey who have been fighting for autonomy since 1984. The conflict has claimed the lives of 37,000 people.
Turkey has not ruled out military incursions into Iraq to hunt separatist Kurds, despite warnings from the U.S., which fears that such moves could lead to tensions with the Iraqi Kurdish groups allied with Washington.
Turkish authorities frequently accuse the Democratic Society Party of having links to an outlawed Kurdish guerrilla group, the Kurdistan Workers Party, or PKK, which the U.S. and European Union consider a terrorist group.
Party members frequently are detained and branch offices raided.
