The assault on a branch of Fransabank in the southern city of Sidon came at a time of rising public anger against banks in the small country facing its worst economic and financial crisis in decades. There was no immediate comment from bank officials.
The attack took place while bank branch was closed. The National News Agency said a police investigation was underway. NNA later reported that cameras in the area showed two people outside the bank at the time of the explosion. It didn't elaborate.
The value of Lebanon's local currency has been in free fall, losing over 60 per cent of its value against the dollar in recent weeks.
The downward spiral was accelerated by the central bank's decision to halt the withdrawal of dollars from foreign currency accounts or transfer bureaus.
The central bank requires private banks to convert withdrawals into the local currency at a market rate set daily.
The decision brought back protests to the streets of Lebanon earlier this week, as demonstrators criticized the central bank governor and private banks and accused them of sequestering their savings in foreign currency.
In a sign of the deepening crisis, Lebanon's prime minister accused the longtime central bank governor of orchestrating the local currency's crash on Friday, and criticised what he called his "opaque" policies that he said covered up major banking sector losses and capital flight.
Lebanon is one of the world's most indebted countries and has been grappling with a liquidity crunch, an economic recession and rising unemployment.
The country has a large diaspora that sends foreign currency home - an income that was already dwindling since last year - and relies on transfers to Lebanese students studying abroad. Many Lebanese keep their savings in foreign currency. (AP) INDIND