Farming and aid groups are warning the conflict between Israel and Hezbollah could affect food supplies in Lebanon and Syria and push hundreds of thousands of people into long-term poverty.

Israel's bombing and ground operations against the militant group Hezbollah has forced residents of key agricultural areas in south and central Lebanon to flee.

That's left farmers unsure of how much damage their lands have suffered from bombing, fire and contamination.

The head of the South Lebanon farmers syndicate, Mohamad Al Husseini, said his region produced many different crops, which could now be lost.

"The south produces around 30 to 40 per cent of Lebanon's olives and olive oil, the south produces 80 per cent of bananas, around 70 per cent of citrus, up to today around 70 per cent of avocado and Asian fruits," he said.

Al Husseini says thousands of Lebanese families depend on these farms and the loss of these crops doesn't just take food off the market, it takes money out the economy and drives up prices.

Israel's repeated bombing of the main border crossing to Syria at Masnaa, which it claims was being used to transport weapons, has also made it impossible for farmers to export.

"All this produce we export to Arab countries through Syria," Al Husseini said.

"The problem is that we will not be able to continue, we will not be able to export our surplus, we will have depression in the market, prices will go down, the farmer won't be able to sell as they want, we will have a very big problem."

Farmers are also concerned about contamination — particularly from Israel's documented use of white phosphorus — and unexploded ordnance from the bombing.

Israel also bombed the main channel carrying water from the Litani River Irrigation Project, Lebanon's largest water source, to hundreds of farms.

The project director, Sami Alawiye, said the irrigation infrastructure required extensive repairs.

"Our facilities are civilian ones, with no military use, there is no reason at all that it should be attacked," he said.

"When the project is threatened it threatens thousands of families, not only the families that work in orchards but also thousands who work in the distribution chain to get the produce to the final consumer.

Lebanon was already in an economic and political crisis before Hezbollah began attacking Israel last year, triggering the current conflict.

The director of the World Food Program in Lebanon, Matthew Hollingworth, says 23 per cent of Lebanese were already considered to be acutely food insecure before Israel intensified its bombing campaign and began ground operations in September, causing mass displacement.

"Clearly, with 1.3 million people impacted, displaced, dispossessed since the start of this conflict or this escalation of this conflict on the 23rd of September in a very short period of time, having lost their homes, their jobs, their livelihoods, they're living in shelters or in host communities, so the situation is dire," he said.

The World Food Program, other relief agencies and even private Lebanese businesses have been simply trying to feed people who have left or lost their homes.

Hollingworth said the impact of the conflict will go well beyond the need for immediate relief — farms and livelihoods will be affected for some time.

"There's no question that when you look at the peri-urban and rural areas of the south, they were all extremely productive areas," he said.

"So a lot of people that have been forced from those areas because of the conflict will miss their harvest, miss their production timeline and that's going to have an impact on the country moving forward.