The United Nations' top aid official has urged the Security Council to renew a mechanism that provides lifesaving assistance to millions of desperate people in northwest Syria through cross-border deliveries from Turkey.

UN Humanitarian Coordinator Mark Lowcock briefed the Security Council during a virtual meeting Tuesday in which he outlined the urgent need to keep the trucks rolling amid the challenges of the COVID-19 pandemic.

"The cross-border operation for northwest Syria, authorized by the Security Council, is a lifeline for millions of civilians whom the UN cannot reach by other means. It cannot be substituted. Its authorization must be renewed," he said.

"An early decision by the council will avoid disruption of this vital operation and help humanitarian organizations continue the scale-up that the current needs and the prospect of COVID-19 demand. A delay will increase suffering and will cost lives," he reiterated.

According to Lowcock, the UN is supporting COVID-19 preparedness and response across Syria, where the authorities have so far confirmed 58 cases, including three fatalities.

The UN is boosting efforts to expand testing capacity and case investigation, as well as infection prevention and control.

Although a UN humanitarian fund has already disbursed some $23 million for preventative measures, Lowcock said significant shortages in personal protective equipment and other medical items remain.

Zhang Jun, China's permanent representative to the UN, said China pays close attention to the humanitarian situation in Syria.

"We are worried that the humanitarian situation will quickly further deteriorate due to the impact of COVID-19," he said.

Zhang said China welcomes the cease-fire appeals made by the UN secretary-general and his special envoy, calling on all parties to enhance mutual trust and jointly safeguard the well-being of the Syrian people.

Zhang reiterated that the Syrian government bears the primary responsibility for improving the humanitarian situation in Syria, including preventing and containing the spread of COVID-19.

"Its role cannot be replaced," he said, acknowledging that the Syrian government has taken responsive measures to raise public awareness of the virus and reduce the risk of transmission.

"We encourage UN agencies and international communities to help strengthen Syria's capacity to respond to the pandemic," he added.

Zhang said China has provided medical assistance to Syria to combat COVID-19 and will continue to do so.

Concerning cross-border humanitarian assistance, Zhang said he is pleased to see the improvement in the scale of such operations.

"We encourage further cooperation and coordination in this regard," he said.

Zhang called on relevant parties to enhance political dialogue and remove all obstacles that "may hinder cross-border humanitarian access to the northwest and northeast of Syria".

Regarding cross-border humanitarian assistance, Zhang said China's position has been clear and consistent.

"We agree that all forms of humanitarian operations should be fortified to meet new challenges posed by the pandemic and take into full account the need of Syrian people," he said. "Meanwhile, we should remember that the cross-border mechanism was established as a contingency or temporary measure. The sovereignty and territorial integrity of Syria must be respected under any circumstances."

Zhang called on all parties to continue to engage in a Syrian-led and Syrian-owned political process in line with Security Council resolutions.

"Civilians and their livelihood must be protected. In this connection, we reiterate the urgency of the immediate lift of the unilateral sanctions," he said.