Beirut - (AFP) - Relief and human rights organizations are warning of a humanitarian "catastrophe" if the Security Council fails on Tuesday to extend the work of the mechanism for delivering aid across the border to Syria , which constitutes a "lifeline" for millions of people in a country depleted by years of war.

"The renewal of the decision is urgent," Ammar Ammar, regional advocacy and communication officer at the United Nations Children's Fund (UNICEF), told AFP, after "humanitarian aid has become a lifeline, especially for the displaced" in northwestern Syria.

"Without cross-border aid, hunger will increase, patients will not receive treatment, and millions will be threatened with losing support to shelter them," he warns.

In 2014, the UN Security Council allowed aid to cross into Syria through four border points, but it soon reduced it, under pressure from Moscow and Beijing, the two allies of Damascus, to limit it to the Bab al-Hawa crossing on the border between Syria and Turkey.

Tomorrow, Tuesday, the mandate of the United Nations to deliver aid through Bab al-Hawa ends, after it was extended on July 10 for a period of six months instead of a full year.

Major humanitarian organizations anticipate voting every time by pressing for an extension of the mandate, while Russia is pressing to limit United Nations aid to that coming from areas controlled by the Syrian government.

More than four million people live in areas outside the control of the Syrian government in northwestern Syria, about three million of them, the majority of whom are displaced, in areas under the control of Hayat Tahrir al-Sham (formerly Jabhat al-Nusra) in Idlib governorate, while 1.1 million reside in Areas controlled by Turkish forces and their loyal factions in northern Aleppo.

Bab al-Hawa crossing secures more than 80 percent of the population's needs, according to the United Nations, which delivers through it food and medical aid, including vaccines, and essential supplies such as blankets and mattresses.

Human rights activists accuse the Syrian government of obstructing aid from reaching areas outside its control.

"It would be disastrous, given that there are no other alternative solutions," Diana Semaan, Syria researcher at Amnesty International, told AFP.

"During the last two years, the number of convoys that were able to cross from government-controlled areas into northwestern Syria did not exceed the number of fingers on one hand," she added.

On Sunday, the last aid convoy entered from the Syrian government-controlled areas to northern Idlib, across the lines of contact between the two sides.

And the President and CEO of the International Rescue Committee, David Miliband, said in a statement Friday that "members of the Security Council should act according to humanitarian imperatives rather than politics."

He stressed that "expected and safe assistance should not be subject to negotiation. In times of increasing needs, what is required is greater access, not less" of cross-border aid.

Over the years, the vote on the extension has turned, according to MSF, into a "tool of political negotiation."

The head of the organization's mission to Syria, Francisco Otero y Villar, said in a statement Thursday that stopping the work of the mechanism means that "hospitals will be closed because they will not be able to pay the salaries of their workers, and that clinics and medical centers will operate without basic medicines such as insulin."

In northwestern Syria, the official in the Idlib Health Directorate (opposition) Hussam Qara Muhammad warned during Sunday's sit-in of a "medical tragedy" that may affect 41 health facilities, including hospitals and specialized centers, if the mechanism stops working.

Medical facilities depend primarily on foreign aid in order to provide hospitalization and health care for the population, after battles over the past years have put dozens of major facilities out of service.

In a joint statement last week, the directors of several UN organizations, including the World Health Organization, the United Nations High Commissioner for Refugees and the World Food Organization, confirmed that the majority of the region's population are "women and children who need this assistance to survive during the height of winter and amid an outbreak of cholera" that is spreading. in Syria for months.

After nearly 12 years of conflict, the majority of Syrians today are below the poverty line, and 12.4 million of them suffer from food insecurity and harsh living conditions, in light of an exhausted economy.

"Year after year, the economic and humanitarian situation is getting worse throughout Syria (...) Therefore, stopping cross-border aid now would be tantamount to a death sentence for many," Heba Ziyadin, Syria researcher at Human Rights Watch, told AFP.