DAMASCUS, June 24 (Xinhua) -- The Islamic State (IS) group and remnants of other extremist factions remain the biggest security challenge to Syria, spokesman of Syrian interior authorities Noureddin al-Baba said Tuesday, following the arrest of suspects linked to a deadly suicide bombing at Mar Elias Church in Damascus.

At a press conference in the capital Damascus, al-Baba stressed that IS poses a cross-border threat that endangers multiple countries, not just Syria.

Syria's interior authorities announced Monday that they had dismantled the IS-affiliated cell responsible for Sunday's suicide bombing at the church in the Dweilaa neighborhood, which killed at least 25 people and wounded more than 60. The attack marked the deadliest of its kind in the Syrian capital in years.

According to al-Baba, a series of raids in rural Damascus following the suicide bombing resulted in the arrest of the entire cell, as well as the seizure of explosives and weapons. Al-Baba confirmed that the group operated independently of any local religious authorities.

Al-Baba said that the interrogation of a captured militant led authorities to the locations of all the cell's hideouts. He identified the ringleader as Mohammad Abdel-Ilah al-Jumaili, also known as Abu Imad al-Jumaili, a Syrian national from the al-Hajar al-Aswad area of Damascus and a former Islamic State figure known as the "desert governor."

The two attackers behind the Church bombing, including one who detonated his explosive vest inside Mar Elias Church and another who was captured en route to the Sayyida Zainab Shiite shrine in the Damascus countryside, were foreign nationals who had entered Syria through the desert after escaping from the al-Hol camp.

The spokesman said IS recruited them as part of a broader effort to exploit security gaps following recent transitions in Syria's governance.

"The misguided youth who had been in al-Hol camp are being recruited by IS under the banner of revenge or retribution," al-Baba warned.

While describing the recent arrests as a "crushing blow" to IS in the capital and surrounding areas, he pledged that Syria will continue working with neighboring countries to confront the "transnational terrorist threat."