The border outpost in Turkey's Kilis province was reportedly attacked on Thursday from a region inside Syrian territory, under IS control.

"Turkish soldiers returned fire after shots came from the Syrian side of the border, from the region where Islamic State militants are. The clash is going on at the moment," a official said.

Reports later followed of Turkish F-16 jets taking off from airbase and heading towards the border area. Tanks and armored vehicles were also being deployed.

Suicide bombing

The offensive came amid a surge of violence on the Turkish-Syrian border this week, which began with a suicide bombing on Monday in the southern town of Suruc. Thirty-two people died and more than 100 were wounded in the attack.

Authorities identified a 20-year-old Turk who had links to "Islamic State" (IS) as a suspect in the bombing, after his identity card was reportedly found at the site.

According to Turkish officials more than 500 people have been detained on suspicion of working with IS in the last six months. Twenty-one terrorism suspects were also arrested this month in an investigation of recruitment networks in Turkey.

IS recruitment

As tensions rise in Turkey's southern region, the government's Syria policy faces ever-growing scrutiny from the international community with lack of sufficient border controls being blamed as the source of many prblems.

Analysts have also warned that the government is failing to adequately address the problem of violent extremists.

"It seems there is not enough focus on stopping Turkish people from joining the Islamic State," said Aaron Stein, a Turkey analyst at the Royal United Services Institute.

As the fear of IS cells grows, Turkish terrorism experts are warning of further attacks within the country.

ksb/rc (Reuters, AFP, AP, dpa)