The al-Nusra Front terrorist group - al-Qaeda branch in Syria - has detained members of the train-and-equip program for Syrian militants.

The al-Nusra Front terrorist group - al-Qaeda branch in Syria - has detained members of the train-and-equip program for Syrian militants, an official of the US Department of Defense said Tuesday.

Since last week, reports from inside Syria have been claiming that al-Nusra has captured at least five fighters trained by the US and coalition forces.

"We have indications members of the New Syrian Forces have been detained by al-Nusra Front in Syria," U.S. Defense Department Spokeswoman Elissa Smith said.

"We are monitoring the situation but have no further details to provide," Smith told media outlets.

Moreover, sources told Anadolu Agency that the so-called Free Syrian Army was trying to persuade al-Nusra group to release the militants.

The al-Nusra Front is on the US list of terrorist organizations due to its links to Al Qaeda.

The train-and-equip program has been jointly organized by the US and Turkey to help prepare Syrian opposition fighters in the campaign against the so-called 'Islamic State of Iraq and the Levant' (ISIL) takfiri group and the national Syrian army.

A total of 54 Syrian opposition fighters went into the country earlier this month after they completed their training at the beginning of July.

The effort to train Syrian opposition groups is part of an overall campaign to allegedly defeat ISIL terrorists who have seized large parts of Syria and Iraq since June last year.

Saudi Arabia, Qatar and Turkey agreed to help opposition groups to fight ISIL and to battle the national army. However, western media reports reveal that ISIL receives the Saudi, Qatari, Turkish support with money and trained mercenaries.

The group also gets direct support from the Zionist entity, by treating its wounded inside the occupied territories.

The US and Turkey signed an agreement on February 17 that allowed up to 1,000 US troops to participate in the training.