Syrian government and Russian warplanes on Saturday targeted the southern edge of Idlib province in what activists described as the most intense airstrikes in weeks, ratcheting up military pressure on the densely populated rebel-held bastion.
A top United Nations official warned Monday that an attack on rebel-held parts in Syria's Idlib in coming months could lead to this century's worst loss of life as government forces pounded the area from the air and ground.
Assad has reportedly given the green light to deploy chlorine gas as his military continues to bombard the northwestern province in a bid deal a winning blow in the country's seven-year civil war.
Asked whether Iran shared concerns about a possible humanitarian catastrophe in Idlib, Jaberi Ansari replied: "We are anxious too".
Meanwhile, the Syrian government began a new round of artillery and rocket shelling in southern Idlib, and adjoining northern Hama Province, according to the Syrian Observatory for Human Rights, a monitoring group.
The situation in Syria is escalating.
Several Middle East TV channels and a United States news channel have been sent to Jisr al-Shughur in Syria's Idlib Governorate to produce the footage needed for the provocation, a statement by the Russian Center for Syrian Reconciliation said.
Turkey has already taken in over three million refugees from Syria and Ankara fears any large offensive will lead a new refugee influx of up to two million from Idlib.More news: Meghan Markle's wears blue Jason Wu to 100 Days To Peace concert
About 3.5 million people are crammed into Idlib and the surrounding areas, at least half of whom have fled vanquished opposition areas.
But Russian President Vladimir Putin this week called for the "total annihilation of terrorists in Syria", while Iranian President Hassan Rouhani spoke of "cleansing the Idlib region of terrorists".
OCHA spokesman David Swanson told Reuters that as of Sunday, 30,542 people had been displaced from northwest Syria, moving to different areas across Idlib.
The Assad regime has twice been targeted by USA air and missile strikes after previous alleged chemical attacks, and U.S. officials have in recent days said additional action would follow if Assad were to use the banned weapons in rebel-held Idlib.
"They hit with four rockets so we escaped with our flock", he said.
Russian Federation and Iran backed a military offensive to reclaim the last major rebel-held area of Syria, while Turkey called for a ceasefire to prevent mass casualties among the province's estimated 3.5 million population.
Violence has displaced 30,000 people in Idlib and the adjacent province of Hama this month alone.
We want to tell you: if you sell Idlib or other opposition-held areas, we're going to buy Reyhanli from you.
"The Turkish border is sealed, the Turks have kept that border quite tightly shut for the past few years, so al-Assad's opponents don't have anywhere to run to", she said.