BAGHDAD: Prime Minister Nuri al-Maliki has sent extra troops to secure the border with Syria and on Saturday hit out at countries he says are giving terrorists the shelter needed to mount attacks inside Iraq.

Maliki signalled no let-up in a worsening row with its neighbour for allegedly harbouring bombers who wrought devastation on Baghdad last month, and broadened his attack to include other nations.

"We will always look for a process of closing all the doors that the assassins can breathe from again. We blame our brothers and our friends and neighbouring countries," he told an audience in the southern city of Karbala.

"They told us they are with us; they have stood with us in certain situations, but what can we say about their support for the killers again?

"The world is either collaborating or forgetting, even Iraqis are forgetting who have committed crimes. The world is embracing them, some of the Iraqis applaud them," Maliki said in a televised speech.

He did not specify the countries to which he was referring.

The border between Iraq and Syria stretches for 725 kilometres (450 miles) and the United States has also blamed Syria for having lax controls that allow insurgents, including Al-Qaeda-linked rebels, to cross over.

Relations between Iraq and Syria plummeted after Maliki alleged that Damascus was sheltering leaders behind one of two deadly truck bombings in Baghdad on August 19, attacks that left 95 people dead and hundreds wounded.

The attacks at the finance and foreign ministries culminated in the worst day of violence seen in Iraq for 18 months.

On Saturday, the police chief of Anbar province confirmed that police and soldiers had been sent to the Syrian border to strengthen security, although he would not specify how many.

"The prime minister ordered us to deploy new forces from the army and police on the border line between Iraq and Syria to prevent infiltrators from entering," Major General Tariq al-Assal told AFP.

Relations between Iraq and Syria have plunged further since the recall of their respective ambassadors on August 25, after Maliki had unsuccessfully asked that two men accused of planning the finance ministry attack be handed over.

The Iraqi premier is calling for an international probe of last month's truck bombings and has asked the United Nations to establish an independent international commission to investigate.

"The magnitude of these crimes demands that they be addressed immediately by the international community," Maliki said in a letter to UN Secretary General Ban Ki-moon.

On Thursday, the premier also accused Syrian intelligence of having hosted a July 30 meeting near Damascus, that he says was attended by Iraqi Baathists and Takfiris.

The Baath party is an outlawed Sunni organisation, some of whose members remain loyal to executed dictator Saddam Hussein. Takfiris are Sunni extremists.

Maliki said on Monday that 90 percent of foreign terrorists who infiltrate Iraq did so via Syria.

Syrian President Bashar al-Assad dismissed his allegations as "immoral" and politically motivated.