A senior Iranian official has said that Tehran will supply the Lebanese army with military equipment to be used in fighting armed groups.
Ali Shamkhani, secretary of Iran's Supreme National Security Council, told reporters in Beirut on Tuesday that the details would be announced during an upcoming visit by Lebanon's defence minister to Tehran.
A diplomatic source told the Reuters news agency that the Iranian defence minister would soon ask his Lebanese counterpart for a list of weapons needed by the army.
Shamkhani is expected to meet Lebanese officials, including Prime Minister Tamman Salam and Speaker Nabih Berri.
The Lebanase army has been stepping up efforts to prevent Sunni Muslim fighters from Syria entering Lebanese border towns.
Last month, armed fighters crossed into Lebanon from Syria, capturing 20 soldiers and policemen. Two of the soldiers have since been beheaded and one has been killed in captivity.
Iranian military support would boost Lebanese security forces that are already backed by Saudi Arabia and the US, as the nearly three-year-old civil war in Syria continues to spill over to Lebanon.
The rise of armed groups in Syria such as the Islamic State of Iraq and Levant (ISIL) presents a shared foe for Shia-majority Iran and its rivals, Saudi Arabia and the US.
Sunni Muslim fighters in Syria and their allies in Lebanon accuse the Lebanese army of working with Hezbollah, the Iranian-funded Shia movement that has sent fighters to help Syrian President Bashar al-Assad's forces.