Syrian state media is accusing militant groups of preventing civilians on Saturday from leaving the last rebel-held stronghold in the country's northwest through a corridor government troops are securing.
The government has used such passageways before to allow residents to flee areas it is besieging ahead of a military offensive.
Last month, Syrian officials declared a "humanitarian corridor'' at the southern tip of the stronghold while troops besieged the area.
State-run TV al-Ikhbariya said no civilians came out via the corridor from Idlib province, controlled by militants dominated by jihadist groups, for the second straight day. Al-Ikhabariya said 20 vehicles were barred by militants from reaching the Abu Dhuhur crossing, including by shooting at those looking to leave.
State news agency SANA also said militants shot at motorists in Idlib, denying them an exit. There was no independent confirmation.
The Abu Dhuhur crossing links between rebel-controlled Idlib, home to nearly 3 million people, and government-controlled areas. State television stations showed buses and medical teams waiting at the crossing.
U.N. and aid groups question the government's use of such corridors amid military offensives and sieges and in the absence of any independent monitors. The U.N. says such exit corridors should be guaranteed from all sides to allow people to use them voluntarily.
Syrian forces have made major ground advances on rebel-held Idlib in recent weeks despite a short-lived cease-fire. The government military offensive since late April has forced nearly half a million people to be displaced within the stronghold, and left about 1,000 killed.
David Miliband, who heads the aid group International Rescue Committee, told a U.N. panel on northwest Syria Friday that the breakdown of the recent ceasefire "makes us fear that the worst may be yet to come.'' He called for an immediate end to the violence against civilians and an accountability mechanism to investigate attacks against civilians.
IRC supports 24 health facilities and 19 ambulances across northwest Syria, including eight who came under attack. Since April, 51 health facilities have come under attack, mostly in government airstrikes.