The United States has accused Russia and the Syrian government of violating the Eastern Ghouta ceasefire at a United Nations Security Council meeting.
The 30-day ceasefire, enshrined in Resolution 2401, was voted for unanimously by members of the Security Council on Saturday.
It came on the back of an offensive launched by the Bashar al-Assad's forces, with the support of Russian warplanes, on the enclave that began on February 18 and has resulted in the deaths of more than 550 civilians, the Syrian Observatory for Human Rights war monitor said.
Speaking on Wednesday, the US representative to the UN Kelley Currie condemned the Syrian government's continued aerial bombardment on Eastern Ghouta, a rural area outside of the capital Damascus that has been under opposition control since 2013.
"Despite the unanimous call for a ceasefire, the regime's attacks continued unabated," Currie said. "Hundreds of Syrians have been killed or injured since we passed the resolution on Saturday."
"Such an attack demonstrates Syria's complete and utter contempt for this council and the United Nations," she added.
On Monday, Russia, a key ally of Bashar al-Assad, said it will implement five-hour "humanitarian pauses" to allow for the evacuation of civilians and the entrance of aid convoys. However, shelling and air raids did not stop and have resulted in the deaths of at least four people.
Currie described Russia's humanitarian pauses as "cynical, callous and in flagrant defiance of the demands of 2401".
Stranded in Eastern Ghouta
Residents of the enclave said government warplanes launched several attacks in the early hours of Wednesday, and stressed the most intense have been in three towns - Douma, Misraba and Harasta - near the front lines.
"There have been no evacuations whatsoever - not medical, not humanitarian, nothing," one resident, who asked to remain anonymous, told Al Jazeera.
"The regime has launched a psychological game - that's all. Bombardment has been ongoing since last night."
Al Jazeera's correspondent Osama Bin Javaid said many people are still stranded in Eastern Ghouta.
"The second day of this so-called truce or pause went away without any major developments on the ground," he said, speaking from the Turkish border city of Gaziantep.
"No aid convoys went inside because the United Nations and other aid workers have been saying that this is too short of a window without any guarantees of whether they would be able to make it back."
Bin Javaid also said rebels in Eastern Ghouta, which has been besieged by government forces since mid-2013, have no faith in the UN.
"More air strikes and more shelling is being reported on Eastern Ghouta and rebels are saying that the UNSC resolution is just words," he said.
Vassily Nebenzia, the Russian ambassador to the UN, told the Security Council that Russia is doing everything it can to ensure the effectiveness of the daily five-hour humanitarian pauses, but blamed rebel forces for targeting the corridors designated for humanitarian operations with mortar shelling.
"We trust that the opposition leaders have a serious-minded approach and that their words will be met with deeds," he said.
"We understand that terrorists remain a legitimate target for military operations and that there will be no ceremonial approach for them," he continued, adding efforts must be undertaken to "effectively neutralise" the presence of the al-Qaeda offshoot in Eastern Ghouta, Jabhat Fateh al-Sham, formerly known as al-Nusra Front.
Speaking from the UN headquarters in New York, Al Jazeera's diplomatic editor James Bays said some rebel factions were looking for a truce.
"It's worth noting that some of the armed groups have actually written to the Security Council saying they are willing to support the ceasefire and are willing to kick any al-Nusra Front elements out of Eastern Ghouta," Bays said.