Israeli forces caught five Sudanese men who tried to illegally enter the country across the Lebanese border overnight and sent them back, the army said in a statement.
A military spokeswoman said it was believed the men had intended to seek work in Israel, which was home to more than 6,000 Sudanese asylum seekers as of January.
The Lebanese army said it had detained "five Sudanese people" near the Israel border for their illegal presence there and was investigating them.
Israel and Lebanon are technically at war, with the Jewish state having fought a full-fledged war against Hezbollah, the Iran-back Lebanese militia, in 2006.
Israel also remains technically at war with Sudan, which supported hardline Islamists - including, for a period, Al Qaeda - under former president Omar Al Bashir.
In February, the leaders of both countries met in Uganda for what the Israeli prime minister's office described as talks aimed at normalising ties.
