Turkish security forces have shot and killed two suspected Islamic State militants on the country's border with Syria who were believed to be planning terror attacks in Ankara.

The private Turkish television station NTV reported one of the two Syrian nationals was wanted in Turkey on suspicion of planning attacks in the capital Ankara or in the southern city of Adana.

The Associated Press reported the two IS (Isis/Daesh) figthters were killed as they tried to enter Turkey. Apparently the pair ignored security warnings. It was not clear whether they had tried to enter the country illegally.

The shootings follow a terror attack on Istanbul's Ataturk airport. Forty-two people were killed and 239 wounded after three gunmen, wearing suicide vests, opened fire on bystanders and detonated their devices. Turkey held a day of mourning yesterday (29 June) in the wake of the attack.

Turkish Justice Minister Bekir Bozdağ said that two terrorists detonated their suicide vests in a waiting area as they approached metal detectors. He added that another attacker fired with a Kalashnikov rifle.

Police inside the building reportedly fired shots to try to stop the attackers just as they reached a security checkpoint at the arrivals hall, but they blew themselves up when they came under fire.

No group has claimed responsibility for the attack, however Turkish officials have said they believe the assault was carried out by IS. While Istanbul and other cities and towns across Turkey have been targeted by both IS and Kurdish militants. IS has predominantly attacked civilian targets while the Kurdish nationalists carry out assaults on police and military installations.

The Turkish Prime Minister Binali Yildirim has suggested the attack in Istanbul could be linked to steps Ankara took on Monday towards mending strained ties with Israel and Russia. IS has singled out Russia as a target for its attacks after the country intervened in Syria, bolstering the ruling Assad regime.