Jihadists Thinkstock

The United States on Thursday declared a Syrian jihadist group known as the Yarmuk Martyr's Brigade (YMB) a global terrorist threat, AFP reports.

The YMB operates on war-torn Syria's borders with Jordan and the Golan Heights and is accused of kidnapping UN peacekeepers.

"The YMB was formed in August 2012 in Deraa, Syria and has staged attacks throughout southern Syria," the U.S. State Department said in a statement announcing the blacklist.

In 2014 it was tied to Al-Qaeda's Syrian offshoot, the Al-Nusra Front, but it has since reportedly pledged itself to the rival Islamic State (ISIS) group.

Now, the group has also joined Al-Nusra and ISIS on the U.S. government's list of what it calls Specially Designated Global Terrorist entities.

"As a result of this designation, all property subject to U.S. jurisdiction in which the YMB has any interest is blocked," the statement said, according to AFP, adding that Americans “are generally prohibited from engaging in any transactions with the YMB."

According to the designation, the YMB was responsible for at least two mass kidnappings of Filipino UN peacekeepers in the Golan in 2013.

The troops were later released after negotiations.

The designation of YMB follows the State Department’s designation several weeks ago of ISIS's branches in Libya, Yemen and Saudi Arabia.

The three ISIS branches were declared "specially designated global terrorists," a category that imposes sanctions and penalties on foreign persons who pose a serious risk of committing acts of terrorism that threaten American nationals or national security, the State Department said.

The ISIS group in Libya also was named as a "foreign terrorist organization".

AFP contributed to this report.