ANKARA (REUTERS) - Turkish authorities have arrested two alleged members of the Islamic State militant group near the Syrian border on suspicion that they were planning a suicide bombing, officials said on Monday.

The two men had been on the interior ministry's wanted list and were detained on Friday in the southeastern province of Gaziantep, the local governor's office said in a statement. They were believed to be plotting suicide attacks in Gaziantep or other cities, according to the governor's office.

Two other men were also detained alongside the two would-be suicide bombers, it said. An official for the interior ministry separately confirmed the detentions of the four.

Gaziantep is near the Syrian border and part of it lies just across the frontier from the Islamic State-controlled Syrian town of Jarablus.

Turkey, which faces multiple security threats, is on heightened alert after four suicide bombings already this year, two of which have been blamed on Islamic State.

The most recent, a suicide bomb attack in Istanbul's most popular shopping district on March 19, killed three Israeli tourists and an Iranian and wounded dozens of people. The government later identified the bomber as an Islamic State member from Gaziantep.

One of the attackers in the March 22 Brussels suicide bombings was deported from Turkey last year after being detained in Gaziantep. Turkey informed Belgium that the man, Ibrahim el-Bakraoui, was a militant, but he was later released by Belgian authorities, Turkish President Tayyip Erdogan has said, calling the decision an intelligence failure on the part of Europe.

As part of a US-led coalition, Turkey is fighting Islamic State in neighbouring Syria and Iraq. It is also battling Kurdish militants in its southeast, where a 2-1/2-year ceasefire collapsed last July, triggering the worst violence since the 1990s.

The spate of bombings has raised questions about Turkey's ability to protect itself from a spillover of both the Syria and Kurdish conflicts.