US troops mounted a major offensive on Thursday in the town, which is about 100km east of the Syrian border.

A local health official said 22 people had been killed and more than 70 people wounded.

A Turkish foreign ministry statement said Turkey was very worried about civilian casualties. 

"We have asked the US authorities to stop the offensive in Tal Afar as soon as possible and avoid excessive and indiscriminate force," the statement said. 

Watching developments

Turkey's military also said it was carefully watching developments in Tal Afar, the Anatolia state news agency reported.

US forces have launched a major 
assault against Tal Afar

"We expect the parties concerned to act with common sense," the General Staff said in a statement. 

Turkey's powerful military has long played a major role in politics, but has recently taken more of a back seat under reforms aimed at winning a start date for EU entry talks.

US forces said Thursday's assault in Tal Afar was in response to provocation after they and Iraqi security forces were repeatedly attacked by fighters who had moved into the town. 

CNN Turk quoted a US official saying the offensive was not aimed at Turkmen, and would continue as long as it was deemed necessary. 

Turkey regards northern Iraq as part of its sphere of influence, not only because of its close ethnic and linguistic links with Iraq's Turkmen minority, but because of the presence of large Kurdish populations on both sides of the border.