Al-Maliki has said that 90 per cent of foreign fighters entering Iraq arrive via Syria, including fighters he blames for two bomb attacks that killed nearly 100 people outside ministries in Baghdad in August.
"There is a government accusation against Syria relating to the bomb attacks... They have information that there is a threat from Syria," Yusuf said.
"We have caught two infiltrators trying to enter in the last two months."
Iraq's government has blamed supporters of the outlawed Baath party of Saddam Hussein, the late president, and al-Qaeda for the August 19 attacks, and said Baath leaders plotted the bombings from Syrian territory.
Bashar al-Assad, the Syrian president, has called Iraq's accusations "immoral" and demanded Baghdad provide proof.
"Syria doesn't have many friends in the West or around the region, so that could play into the hands of those who want to accuse Syria"
Fares Braizat, Middle East analyst, Qatar University
Hoshyar Zebari, the Iraqi foreign minister, said on Friday that Syria had been given evidence through Turkish mediators.
"We have given them the evidence that we have through the Turkish foreign minister and we are waiting for their response," he said.
Fares Braizat, a Middle East analyst at Qatar University, told Al Jazeera that Iraq's act is being seen as an "escalation" and of "provoking the Syrians even more than previously".
"The current Iraqi government under al-Maliki feels that ... by raising the stakes with Syria, they can gain new friends who can support them especially when taking that case to the UN Security Council in order to create an international court to try those responsible."
Al-Maliki has formally asked the UN Security Council to launch an inquiry into the Baghdad bombings.
"Syria doesn't have many friends in the West or around the region, so that could play into the hands of those who want to accuse Syria and take Syria into another level of confrontation," Braizat said.
"The Syrians will have to continue to resist this pressure."
Following the Baghdad explosions, Iraq withdrew its ambassador to Syria. Damascus in turn recalled its ambassador to Iraq.
Syria and Iraq were ruled for many years by rival wings of the Baath party and were at odds after Saddam came to power in 1979. Both political and economic ties improved in the late 1990s.
Tensions re-surfaced after the US-led invasion in 2003 assissted the formation of a Shia Muslim government in Iraq.