Australian jihadists fighting overseas who are "trained killers" and "hate our way of life" should be stopped from returning home and detained if they do, Prime Minister Tony Abbott said Friday.

Australia has concerns that its citizens are fighting alongside Sunni militants in Iraq and Syria, including with the radical Islamic State of Iraq and the Levant (ISIL) group.

The number of people driven from their homes by conflict and crisis has topped 50 million for the first time since World War II, with Syria hardest hit, the U.N. refugee agency said Friday.

The UNHCR said there were 51.2 million forcibly displaced people at the end of 2013, a full six million higher than the previous year.

Indonesians are joining the procession of jihadists to Syria and Iraq, sparking fears they will revive sophisticated militant networks when they return and undermine a decade-long crackdown that has crippled the most dangerous cells.

Support for groups like the Islamic State of Iraq and the Levant (ISIL), Sunni radicals currently rampaging through northern Iraq, is growing among Indonesian extremists with dozens believed to have joined the insurgency.

The army boosted its security measures after obtaining information of a terrorist act planned by a group linked to Sheikh Sirajeddine Zuraiqat, the religious guide of the Abdullah Azzam Brigades.

According to As Safir newspaper published on Friday, Zuraiqat is currently in Syria in an area close to the border with Lebanon.

France called Thursday for an urgent but also political response from Iraq to the offensive by jihadist ISIL forces, and said it was "ready" to contribute to reinforcing the democratic opposition in Syria. 

The Iraq crisis, where ISIL forces have seized control of large swathes of the country north of Baghdad, is "a dramatic consequence of the situation in Syria", said the French presidency in a statement.

A Danish freelance photographer has been freed after being held hostage in Syria for 13 months, the Danish government said late Thursday.

Daniel Rye Ottosen was captured in Syria on 17 May last year after travelling to the country to "document the conflict and the living conditions of civilians, especially children," his family said in a statement emailed by the foreign ministry.

The British government on Thursday banned the ISIL militant group currently cutting a swathe through northern Iraq, adding it to a list of proscribed organizations along with four other groups linked to the Syrian conflict.

Security Minister James Brokenshire told lawmakers that terrorism related to the civil war in Syria "will pose a threat to the UK for the foreseeable future", and said banning the groups sent a "strong message".

A car bomb in Homs in central Syria Thursday killed six people in an Alawite-majority neighbourhood of the city, a monitoring group said as state media gave a lower toll.

Syrian warplanes Thursday launched 23 air raids on Mleiha southeast of Damascus, a key rebel bastion President Bashar Assad's regime has struggled for weeks to recapture, a monitor said.

Regime ground forces also targeted the Mleiha area with nine surface-to-surface missiles, as troops backed by Lebanon's Hizbullah battled rebels and their jihadist Al-Nusra Front allies, the Syrian Observatory for Human Rights said.

Brig. Gen. Maher Assad, head of Syria's Republican Guard and the army's elite Fourth Armored Division, has reportedly appeared in a recent picture for the first time in four years, ending speculation about his fate after media reports said he was killed or injured in the Syrian civil war.

The powerful general, thought by some to be the second most powerful man in Syria after his brother Bashar, showed up flanked by renowned singer George Wassouf in a picture that was posted Wednesday on Twitter.