Turkish security forces killed one suspected Islamic State (ISIS) militant seeking to cross into Turkey from Syria and arrested 21 others, the army said Wednesday.

The suspected ISIS militant killed on Tuesday was part of a group seeking to illegally cross the border neighbouring the Kilis region of southern Turkey, the army said in a statement.

"Twenty-one people, including nine children, were detained," it added, giving no further details or the nationality of those arrested.

The incident comes as Turkey seeks to step up efforts to crack down on ISIS jihadists crossing its border, amid signs Ankara is taking the security threat posed by the group increasingly seriously.

Turkish security forces on Saturday killed four suspected ISIS militants near the Syrian border in the southeastern province of Gaziantep, security sources said.