A Jordanian court on Monday sentenced a Syrian man to death by hanging for carrying out a "terrorist" attack in 2016 that killed seven soldiers near a border crossing.

Three other Syrians initially given the death penalty were jailed for life and a fifth received a two-year sentence, said an AFP reporter who attended the hearing at the state security court.

All five were arrested and put on trial in March after a June 2016 suicide bombing killed seven soldiers and wounded 13 in no-man's land near the Rukban border crossing with Syria.

Soon after the attack, the army declared Jordan's vast desert regions stretching northeast to Syria and east to Iraq "closed military zones".

The move stranded tens of thousands of Syrian refugees in the area and sparked calls by international relief agencies for Jordan to ease the measure.

The military court sentenced Najm al-Umur, 21, to death by hanging after he was convicted of "terrorist activity leading to the death of individuals".

Umur, considered to be the mastermind behind the attack, was described in the charge sheet as a member of the Islamic State group.

Three other defendants, all in their 20s, were also sentenced to hang but had their sentences commuted to life in prison after the court took into consideration a number of reasons, including that their role had been only to provide support.

The fifth defendant was sentenced to two years in prison for entering Jordan illegally.

The charge sheet said he was sent to the country to plan the attack and had recruited the others.

Jordan is a member of the US-led coalition fighting IS.