United Nations humanitarian agencies say they are searching for a new route into southern Lebanon to help war refugees, after Israel imposed an indefinite ban on movement in the region.

A spokeswoman for the U.N. World Food Program, Christiane Berthiaume, said Tuesday relief agencies are looking for alternative ways to provide aid to Lebanese civilians cut off by heavy fighting.

Aid officials say road transport is too dangerous after the Israeli military warned it would strike any vehicle traveling south of the Litani River on suspicion of transporting weapons.

The U.N. spokeswoman said there are hundreds of thousands of people who need aid in Lebanon. The World Food Program has brought 404 tons of food into the region, but she said that is not enough.

Some information for this report provided by AP, Reuters and AFP.