Tran Thanh Cong, Vietnamese ambassador to Egypt with concurrent charge for Lebanon, said the woman, who works as a house helper for a family, had an arm broken by falling objects as a result of the blast.

She has been hospitalized and is in stable condition.

Around 50 Vietnamese live in Lebanon, mostly in Beirut, Cong said.

Vietnamese officials in Egypt would help Vietnamese citizens in need following the blast, and would go to Lebanon for certain requirements, he added.

The explosion, which occurred at a port warehouse that stored highly explosive materials, was the most powerful in years in the city, Reuters reported.

At least 78 people were killed and around 4,000 were injured, according to Lebanese Health Minister Hamad Hasan.

President Michel Aoun said 2,750 tons of ammonium nitrate, used in fertilizers and bombs, had been stored for six years at the port without safety measures.

He has called for an emergency cabinet meeting on Wednesday.

Officials did not say what caused the blaze that set off the blast, but local media said it was started by welding work being done on a hole in the warehouse.