The offensive against the last stronghold of the Islamic State in Syria is intensifying

Kurdish-Arab forces on Monday continued the "last" offensive against the Islamic State (IS) group's last stronghold in eastern Syria, where several hundred jihadists oppose fierce resistance.

EI virtually lost all its conquered territories in 2014, proclaiming a "caliphate" straddling Syria and Iraq and occupying an area equivalent to that of Britain.

Now the jihadists, heavily weakened by multiple offensives, are stuck in a small pocket of resistance in the eastern province of Deir Ezzor, near the Iraqi border.

The Syrian Democratic Forces (SDF) on Saturday launched the final badault on ISIS positions in this sector, where the number of jihadist fighters can reach about 600, mostly foreigners, according to this Kurdish-Muslim alliance. Arab supported by Washington.

"The SDS is slowly progressing in the rest of the resistance pocket of the IE," said Monday the Syrian Observatory of Human Rights (OSDH), which has an extensive information network in Syria.

"There are sporadic aerial bombardments and especially artillery fire from the international coalition" led by Washington, said OSDH director Rami Abdel Rahman.

Snipers, buried mines and tunnels dug by jihadists slow the advance, according to this source.

Since the fighting intensified, more than 37,000 people, mostly women and children of jihadist fighters, have moved to areas under SDS control.

This number includes some 3,400 people intercepted by the FDS, suspected of being ISIS fighters, who sought to infiltrate the displaced to escape the siege.

Some 600 people left the redoubt Sunday, according to the OSDH.