ZAATARI, Jordan: The United Nations Children's Fund has agreed with the Syrian government to expand humanitarian work across the country in a move that could save tens of thousands of lives, UNICEF chief Anthony Lake said on Monday.

Activists say more than 30,000 people have been killed in the 18-month-old uprising against President Bashar al-Assad, but with 1 million people displaced the approaching winter poses as much of a threat as the relentless violence.

Lake said the agency's agreement with Syria will allow it to go beyond its Damascus operations to reach Syrians in conflict areas. It aims to vaccinate within a couple of months 1 million vulnerable children against diseases such as measles, he added.

"The Syrian government has agreed especially in recent weeks to allow us to work with a number of local groups that will allow us to address the needs of the people," he told Reuters at a refugee camp for 30,000 Syrians in northern Jordan.

The deal will expand UNICEF's partnership with more than 40 Syrian civil groups and the Syrian Red Crescent, he said.

UNICEF has opened an office in the Syrian port city of Tartous and talks were under way with Syrian authorities to open one in Homs, scene of massive damage and the heaviest civilian casualties in a year and a half of conflict,

"We have increased our staff in Syria. We are hoping to establish some local offices," Lake added. "We have a growing opportunity to do much more. We have an opportunity if we can seize it to save and improve hundreds of thousands of lives."

UNICEF plays a lead role along with other humanitarian groups in providing essential services including water, sanitation and education support in Syria.

Lake said it was difficult to estimate how many children had died but it was clear they had borne the brunt of the conflict. "Clearly thousands of children have been killed and tens of thousands and now hundreds of thousands have been uprooted," he said.

Despite a $91 million financing gap to address the needs of displaced Syrians and refugees outside the country, Lake said the agency was planning for a conflict that shows no sign of breakthrough, including looking at supply routes and stockpiles.

But the challenges ahead were daunting with winter coming and more than a million Syrians displaced, more than half of whom are women and children and many of them sheltering in schools, mosques and other public buildings, Lake said.

"Much of Syria (has) story after story of great human suffering, but we can do it and my main message is that we should not throw up our hands and say because of the political difficulties and the escalating violence that there is nothing to be done," he added.

UNICEF figures calculated in collaboration with Syrian authorities show that at least 2,000 schools have been damaged. Many are still housing displaced people despite the start of the school year last month.

"There are tremendous needs across the board in terms of sanitation, in terms of particular interests of education because probably a tenth of schools have been damaged," he said.

"What worries me (is) the generation of even greater numbers of internally displaced people. Unless we can help educate children and help overcome the psychological wounds then we are going to see the hatreds develop that can replicate the conflict in future generations."