A convoy of Kurdish Peshmerga troops departed from Turkey in a convoy overnight to help bolster Syrian Kurds holding out against self-styled Islamic State militants in the besieged town of Kobani.
Islamic State combatants have been trying to capture Kobani, known as Ayn al-Arab in Arabic, for over a month, pressing their assault despite U.S.-led air strikes on their positions and the deaths of hundreds of their fighters.
The United States is investigating reports that Islamic State fighters have used chemical weapons against Iraqi security forces.
US Secretary of State John Kerry said the allegations, reported by the Washington Post, are "extremely serious" and confirmed his department was "seeking additional information" to determine their accuracy.
The Post said poisonous chlorine gas was the diagnosis for 11 Iraqi police officers who were rushed to a government hospital with severe breathing problems after an attack, purportedly by Islamic State extremists, last month.
The newspaper said an official at Iraq's ministry of defence supported the claims of the Iraqi forces, though the report added that details of two other apparent chlorine attacks were "sketchy".
Satellite images have revealed the destruction in and around the town of Kobani, on the Syrian border.
Members of a prominent motorcycle gang from Holland have reportedly joined forces with Kurdish troops in Iraq to fight IS militants.
The sister of a UK journalist being held by Islamic State militants has appealed for his captors to reopen dialogue aimed at freeing him.