TUNIS (REUTERS) - A Tunisian military doctor seeking to retrieve his son who had joined ISIS in Syria was among those killed in Tuesday's suicide attack by militants at Istanbul airport, a security sources said on Wednesday.

Three suspected Islamic State in Iraq and Syria, or ISIS, suicide bombers opened fire and blew themselves up in Istanbul's main airport on Tuesday evening, killing 41 people and wounding 239 in the deadliest in a series of suicide bombings this year in Turkey.

The Tunisian Defence Ministry confirmed that Brigadier-General Fathi Bayoudh, a military hospital doctor, was among those killed.

A senior security source and local media said he had been in Turkey to try and convince his son to leave ISIS.

"Bayoudh travelled to Turkey in an effort to meet his son, who joined the Islamic State in Syria a few months ago with his girlfriend," the Tunisian security source said.

The source said the son had now been detained by Turkish troops on the border with Syria.

"Bayoudh's son travelled with his girlfriend who studied with him at the faculty of medicine a few months ago, which prompted several attempts by his father to persuade him to return," the source said.

Several local Tunisian newspapers online and radio also cited other security sources saying Bayoudh was in Turkey to met his son to try to persuade him to come home.

Tunisia has become a model of democratic reform in the Arab world since its 2011 uprising against autocrat Zine El Abidine Ben Ali. But it is also one of the largest sources of foreign fighters for Islamist groups in Iraq and Syria.

Government officials estimate more than 3,500 Tunisians have left to fight for ISIS and other groups in Syria, Iraq and Libya, some in command positions.

Some are recruited from impoverished areas in the North African nation, but others are professionals and graduates recruited online by Islamic militants.