Osama bin Laden
Osama bin LadenReuters

The son of Al Qaeda's late founder Osama bin Laden has urged jihadists in Syria to unite, claiming that the fight in the war-torn country paves the way to "liberating Palestine."

"The Islamic umma (nation) should focus on jihad in Al-Sham (Syria)...and unite the ranks of mujahedeen (jihadists) there," said 23-year-old Hamza in an audio message posted online.

"There is no longer an excuse for those who insist on division and disputes now that the whole world has mobilized against Muslims," said the terrorist.

His undated message comes after Al Qaeda leader Ayman al-Zawahiri also urged jihadists in Syria to unite, despite his continued rejection of the rival Islamic State (ISIS) group and its proclaimed caliphate.

"The matter of unity today is one of life and death," Zawahiri said in an audio message posted online on Saturday.

"Either you unite to live as Muslims with dignity, or you bicker and separate and so are eaten one by one," he added, according to SITE Intelligence monitoring group.

Al Qaeda's Syria affiliate Nusra Front is a rival of ISIS, which is an Al Qaeda offshoot whose leader Abu Bakr al-Baghdadi in 2014 declared an Islamic caliphate across territory seized in Iraq and Syria.

Bin Laden's son said Syria is the "best battlefield" leading to "liberating Al-Quds," the Arabic name for Jerusalem.

"The road to liberating Palestine is today much shorter compared to before the blessed Syrian revolution," he said.

US intelligence officials have said that Hamza was the favorite son of the 9/11 terrorist mastermind who had been grooming him to take over as Al Qaeda's leader.

AFP contributed to this report.