UNITED NATIONS, Nov. 25  -- The UN humanitarian relief chief said here Tuesday that while humanitarians have made some progress in delivering much-needed supplies to the growing numbers of people in conflict-riven Syria, efforts by the United Nations and its partners are still falling short.

"This is a conflict that is affecting every Syrian," Valerie Amos, the UN under-secretary-general for coordination of humanitarian affairs and UN emergency relief coordinator, said while briefing the UN Security Council on the current humanitarian situation in Syria.

"We have lamented the possibility of a lost generation of Syria 's children: it is now a reality," she said.

Specifically, Amos said Syria's economy has contracted some 40 percent since 2011, with unemployment now exceeding 54 percent. In addition, three quarters of the population live in poverty, and school attendance has dropped by more than 50 percent.

Meanwhile, she noted that Security Council Resolution 2165, which was adopted in July and aims at increasing access to people most in need, has helped the United Nations to overcome some of the challenges faced, by permitting direct delivery to hundreds of thousands of people, complementing the considerable cross-border deliveries conducted by non-governmental organizations.

Since the adoption of the resolution and primarily through cross-border deliveries, supplies had been distributed in nearly all the hard-to-reach locations in the four governorates, leading to a more effective response, she said.

However, no more than two besieged locations have been reached in any month since the adoption of the resolution, and only one location has been reached in each of the past two months.

"Despite the progress we have made, it is still not enough," Amos said. "We have faced considerable challenges in implementing resolutions 2139 and 2165 and continue to fall short of meeting the humanitarian needs of all the people we aim to reach in Syria. "

Security Council Resolution 2139, adopted in February 2014, demands that all parties, in particular the Syrian authorities, allow humanitarian access in Syria across conflict lines, in besieged areas and across borders.

As the resolution was adopted, there were 220,000 people besieged by either government or opposition forces; of those, 212, 000 remain besieged today, she noted.

Amos also emphasized that the 15-nation Security Council should continue to call for an end to the "bureaucratic steps" that hinder the delivery of assistance, as well as push for the inclusion of medical supplies in convoys and call for the lifting of sieges.

Noting that some 12.2 million people -- more than 5 million of them children -- are now in urgent need of humanitarian assistance throughout the country, Amos said that continuing violence has forced nearly half of Syrians from their homes, many of them multiple times.

Consequently, there are now some 7.6 million people displaced inside Syria. In addition, more than 3.2 million people have fled the country, with countries in the region and communities hosting refugees bearing an "enormous burden," Amos said.

The conflict in Syria, which began in March 2011, has reportedly led to over 150,000 deaths, and more than 680,000 people have been injured. It has also spawned a refugee crisis in which some 2.5 million people are being sheltered in neighboring countries, including Lebanon, Jordan and Turkey.

At least 10.8 million people are in need of assistance inside Syria, including at least 6.5 million who are internally displaced, according to UN data.