Israeli air strikes overnight on the main border crossing to Syria had left Lebanon’s main crossing point to its neighbour unable to function, according to the UN’s refugee agency, Al Jazeera reports.

The agency said the attack hindered attempts to flee a country where a fifth of the population is already internally displaced.

Rula Amin, the UNHCR’s Amman-based spokesperson, said she was unaware of any warning before the strike, which landed 500 metres from the main border crossing. Some 430,000 people have crossed from Lebanon to Syria since Israel’s campaign started, she said.

“The attacks on the border crossings are a major concern,” she said. “They are blocking the path to safety for people fleeing conflict.”