Islamist militants holding 19 Lebanese soldiers seized during an incursion into Lebanon said on Friday they had demanded the release of Islamist prisoners in exchange for letting their captives go.

Two commanders close to the group holding the soldiers, speaking by telephone, said the demands had been sent to the Lebanese government and army, which drove the gunmen from the border town of Arsal on Thursday after five days of fighting.

It raises the prospect of a potentially lengthy hostage crisis for the Lebanese authorities.

A security source said the militants had put forward the names of around 20 Islamist detainees they wanted released.

One of the militants, speaking to Reuters, said: "It is simple: their soldiers for the Islamic hostages."

The incursion into Arsal by Islamist militants including fighters from the Islamic State - the same group that has seized territory in Iraq and Syria - marked the most serious spillover yet of the three-year-old Syrian civil war into Lebanon.

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