The Syrian army and its allies reached Deir ez-Zor on Tuesday in a sudden advance into the city after months of steady progress east across the desert.
The United Nations has estimated that 93,000 civilians were living under Daesh siege in Deir ez-Zor in “extremely difficult” conditions, supplied by air drops.
The 40 trucks that reached the area on Thursday carried basic needs such as fuel, food and medical supplies to civilians, and included two mobile clinics, SANA reported.
The army also holds another besieged enclave at the city’s airbase, separated from its advancing forces by hundreds of meters of Daesh-held ground.
The so-called Syrian Observatory for Human Rights said on Thursday that the army has not yet connected with that enclave, and is working on expanding its corridor from the west.
The army expanded its control of ground around the corridor after heavy artillery and air strikes.
Deir ez-Zor is located southeast of Daesh’s main stronghold Raqqa.
Both cities lie in oil-rich areas on the Euphrates River.
Syria has been gripped by civil war since March 2011 with various terrorist groups, including Daesh, currently controlling parts of it.