The Food and Agriculture organization says it has stopped airlifting aid into some of the conflict affected areas due to the recent clashes.
Fighting erupted in parts of Unity State last week between the government and the SPLA in opposition.
FAO says insecurity in the areas has made it impossible to provide seeds and tools to farmers. The planting season has started.
It says it is monitoring the situation and taking any opportunity to provide inputs in more secure areas.
The aid agency targets to assist more than 170,000 food-secure farming families by the end of this month.