Syrians are seen at the borderline in Suruc province of Sanliurfa, Turkey on September 23, 2014 as the Syrians fled from clashes between the Islamic State of Iraq and Levant (ISIL) militants and pro-Kurdish Democratic Union Party (PYD) forces, continue to cross into Turkey Ibrahim Erikan/Getty Images ANKARA (Reuters) - Turkey is erecting a modular wall along part of its border with Syria as well as reinforcing wire fencing and digging extra ditches after a suspected Islamic State suicide bombing killed 32 mostly young students in a border town this week.

Turkey's NATO allies have long expressed concern about control of its border with Syria which in parts runs directly parallel with territory controlled by Islamic State. A suicide bombing on Monday in the southeastern town of Suruc highlighted fears about Syria's conflict spilling onto Turkish soil.

U.S. President Barack Obama spoke by phone with his Turkish counterpart Tayyip Erdogan late on Wednesday, agreeing to work together to "stem the flow of foreign fighters" and secure the 900 km (560-mile) border, the White House said.

Turkish officials have said they believe that the bomber in the Suruc attack was a 20-year old Turkish man who had traveled to Syria last year with the help of a group linked to Islamic State.

"Critical sections (of the border) have been identified. Priority will be given to these areas and measures will be taken with all technological capabilities," Deputy Prime Minister and government spokesman Bulent Arinc told reporters during a break in a cabinet meeting late on Wednesday.

Thousands of foreign fighters are thought to have traveled through Turkey to join Islamic State in Syria and Iraq in the past few years, some of them with assistance from Turkish smuggling networks sympathetic to the militants.

The government's critics say it is acting too late.

A senior government official told Reuters that a 150 km "modular wall", which can broken down into parts and reassembled elsewhere, would be set up along part of the border, while wire fencing in other parts would be reinforced.

Flood-lighting would be installed along a 118 km stretch, while border patrol roads would be repaired, a package of upgrades which would cost around 230 million lira ($86 million), the official said.

The armed forces were also digging a 365 km long ditch along the border and have deployed some 90 percent of drones and reconnaissance aircraft to the Syrian border, the military said.

Turkey's armed forces have already stepped up security along parts of the border in recent weeks, as the conflict in Syria involving Kurdish militia fighters, Islamist militants and Syrian security forces intensified.

Around half of the armored vehicles which patrol Turkey's borders are along the Syrian frontier, the official said. Half of the 40,000 military personnel who guard Turkey's borders - including with Iraq, Iran, Armenia, Georgia, Greece and Bulgaria - are now on the Syrian frontier.

KURDISH TENSIONS

Turkish Kurds watch developments in the Kurdish town of Kobani as they stand near the Mursitpinar border gate in Suruc, Sanliurfa province, Turkey Thomson Reuters The general staff said on Thursday four suspected Islamic State members, accompanied by four children, had been caught trying to cross to Syria in the southern province of Gaziantep on Wednesday, the latest in a string of such detentions.

The Suruc bombing, whose victims included Kurds, enraged Turkey's Kurdish minority, many of whom suspect the government of tacitly backing Islamic State in Syria against Kurdish forces, something Ankara strongly denies.

Kurdish militants claimed responsibility for the killing of two Turkish police officers on Wednesday in what they said was retaliation for the Suruc bombing.

The armed forces also reported a series of attacks by Kurdistan Workers Party (PKK) militant group on Wednesday, though no casualties were reported.

In the eastern province of Tunceli rebels opened fire on a military base, triggering a brief clash. In Van, near the Iranian border, militants set fire to trucks and opened fire on troops, the military said in a statement.

Guerrillas also blocked highways and set fire to vehicles in various provinces across the east of the country.