A Jordanian man was sent to jail on Monday for joining the Al-Qaeda-linked Al-Nusra Front to fight against the Syrian army.

A Jordanian man was sent to jail on Monday for joining the Al-Qaeda-linked Al-Nusra Front to fight against the Syrian army, a judicial official said.

"The man was charged with carrying out acts that the government does not approve and that would expose Jordan to the risk of acts of aggression and revenge," the official told Agence France Presse.

"The convict was arrested in February after he returned from Syria for health reasons," he added.

Jordan has jailed dozens of men convicted of trying enter Syria to fight alongside mercenaries against the national military.

Jordan, home to more than 500,000 Syrian refugees, denies accusations by the Damascus regime that the kingdom has opened up its borders to the so-called jihadist fighters.

Britain's Daily Telegraph on Monday cited a defense study as showing that 'jihadists' and members of hardline Islamist groups make up almost half of forces fighting against the Syrian army, estimated at about a total of 100,000.

The analysis by defense consultancy IHS Jane's estimates that around 10,000 are jihadists fighting for groups linked to Al-Qaeda and another 30,000 to 35,000 are hardline Islamists, who differ from jihadists in that they are concentrated only on the Syrian conflict, and not on the global extremist fight.

Syria was hit by a violent unrest since mid-March 2011, where the Syrian government accuses foreign actors of orchestrating the conflict by supporting the militant opposition groups with arms and money.