Rebel-held Madaya has been blockaded for months by pro-government forces prompting aid agencies to warn of widespread starvation.
Abou Ammar, a media activist in Madaya, told Al Jazeera over the phone that local aid organizations have been waiting since early Monday morning for aid to arrive.
“We have all been eagerly waiting since 5 a.m. The situation here is getting worse and it is about time this operation goes through.
“We will work with the aid convoys arriving in Madaya and will help distributing aid to residents in town,” he said.
The U.N. humanitarian chief Stephen O'Brien said that the arrival of convoys to help civilians in the three towns cut off for months by the war in Syria must not be "either one-off or exceptional."
Syria's U.N. Ambassador Bashar Ja'afari told reporters that the government reiterated its commitment to cooperate fully with the U.N. and the Red Cross to deliver humanitarian assistance to all civilians "without any discrimination," including those in besieged and hard-to-reach areas.
He called reports of starvation in Madaya fabrications and lies and insisted that "the Syrian government is not and will not exert any policy of starvation against its own people." At the same time, however, he said economic sanctions against Syria and the influx of "terrorists from all over the world" are causing starvation and economic and humanitarian problems in the country.
Ja'afari accused Saudi Arabia, Qatar and Turkey of raising the humanitarian issue and "defaming" and "demonizing" the Syrian government in order to torpedo the Geneva talks because "they are not in favor of a political settlement."
Mousa al-Maleh, the head of the local committee in Madaya, told Al Jazeera that four trucks have arrived so far in the town that has been besieged since July.
"Trucks loaded with blankets and food aid have arrived in Madaya and will be distributed with the help of local organisations," he said.
The blockade of Madaya has become a focal issue for Syrian opposition leaders who told a U.N. envoy last week they will not take part in talks with the government until it and other sieges are lifted.
The Doctors Without Borders (MSF) charity said over the weekend that at least 28 people have died of starvation in Madaya since Dec. 1.
“MSF-supported medics in the besieged town have 10 critical starvation patients needing urgent hospitalization,” the group tweeted on Sunday. It added that “200 more malnourished patients could become critical and in need of hospitalization within a week if aid doesn’t arrive.”
The Shia towns of Fuaa and Kefraya have been under siege by Jaysh el Fateh — a collective of opposition groups that includes Ahrar al-Sham and al-Nusra Front — since March 2015.
Anas Maarawi, a media activist in Idlib, told Al Jazeera that four trucks arrived to the towns on Monday.
"The rest are expected to be on their way in. We were told there are 16 others expected, he said.
At least 400,000 are said to be living under siege in 15 locations across Syria, according to the UN.
The International Committee of the Red Cross (ICRC) said 21 trucks were headed for Al-Foua and Kefraya, where some 20,000 people are under rebel siege. Another 44 trucks were headed to Madaya, in Damascus province, where 42,000 people are reportedly trapped.
“Trucks carrying aid left to Al-Foua and Kefraya earlier this morning as the route is longer and requires more coordination,” ICRC spokesman Pawel Krzysiek told Agence-France Presse. “The convoy for Madaya has now begun moving.”
The United Nations said Thursday that the Syrian government had agreed to allow access to Madaya, after the reports of people dying of starvation there began to circulate.
The aid deliveries are being organized by the ICRC, Syria’s Red Crescent, the United Nations and the World Food Program. They include food, milk for children, blankets, and medicine for acute and chronic illnesses, as well as surgical supplies.
Blockades have been a common feature of the nearly five-year-old Syrian war that has killed 250,000 people. Government forces have besieged rebel-held areas near Damascus for several years and more recently rebel groups have blockaded loyalist areas including Al-Foua and Kefraya.
The areas included in the latest agreement were all part of a local cease-fire deal agreed in September, but implementation has been halting.
The last aid delivery to Madaya, which took place in October, was synchronized with a similar delivery to the two villages.
Al Jazeera and wire services