The U.N. is evacuating all nonessential staff from Beirut because of the Israeli military strikes on Lebanon, the world body's refugee agency said Tuesday.

The U.N. High Commissioner for Refugees is closely monitoring the situation, and staff on the ground report that the thousands fleeing to Syria are mostly Syrian nationals working temporarily in Lebanon, said spokeswoman Jennifer Pagonis.

"Nonessential U.N. staff are being evacuated from Beirut," Pagonis said. "Essential UNHCR staff remain on the ground."

Elisabeth Byrs, spokeswoman for the U.N. Office for the Coordination of Humanitarian Affairs, said all 400 international U.N. staff in Lebanon, as well as 88 visitors, had been accounted for and were safe.

UNHCR is also trying to monitor the situation of some 20,000 Iraqi and Sudanese refugees and asylum seekers in Lebanon, Pagonis said.

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UNHCR has already evacuated seven nonessential personnel and family members and three more should leave Tuesday. Some Lebanese staff members have been relocated to safer areas within the country and are in the process of compiling a preliminary needs assessment, she added.

The refugee agency has staff elsewhere in the region and stockpiles of relief items in Jordan and Syria that can be released at short notice.

The Geneva-based International Organization for Migration said it had a team arriving in Lebanon Tuesday to assess the numbers and situation of foreign nationals who need to be evacuated to a third country.

Bangladesh, Moldova, the Philippines and Sri Lanka have already offered to help IOM evacuate their nationals in Lebanon who want to leave, said spokeswoman Jemini Pandya.

"With the situation extremely fluid, the Sri Lankan government said it expects the numbers of its nationals wanting to leave Lebanon to reach the thousands," Pandya said.

There are an estimated 80,000 Sri Lankan migrants in Lebanon, according to IOM.