A Briton in Beirut has described the moment Tuesday’s explosion hit his family home as “the most terrifying experience of my life”.

Jack Kemp, 19, and his family have been living in the Lebanese capital for more than 15 years and the teenager was in their apartment, a little over half a mile (1km) from the blast, when it happened.

“I had a meeting going on, I heard the first blast go off and it was all right, it was a blast, it shook the windows,” Mr Kemp told the PA news agency.

“I was curious as to what happened, so I went to the window, opened the window slightly and looked out. Five to 10 seconds later there was just this massive, massive, massive explosion, and I could see this white wall of whatever it is, the mushroom cloud barrelling towards me.

“I literally turned around, ducked a little bit, and the entire house just exploded. The window frames, which are obviously no longer there, blew across on to the wall and missed the top of my head.

“The most terrifying experience of my life. I will never forget that noise, ever.

“My first thought was my dad – his office is really close to the port.”

Mr Kemp’s father, Andy, had been working less than half a mile from the explosion site and the blast fired glass shards into his head and neck.

The UCL chemical engineering student ran to his father’s office, expecting the worst, and saw first-hand the devastation.

“It was hell on earth, to be honest – people dead on the street, people dead in their cars, people with body parts hanging off, bleeding everywhere, screaming everywhere,” he said.

“He (Andy) was bleeding extraordinarily badly, he was really badly shaken up. But I had gone down there thinking that I was going to be dragging out a dead body. Literally, I was preparing myself to do that.”

Mr Kemp took his father to hospital before walking home. He suffered three gashes to his leg and “escaped with a few stitches”.

Nearly 150 people have been confirmed dead following the blast, while thousands more were wounded and lost their homes.

The UK Government has promised a £5 million support package to aid recovery efforts, and is also sending HMS Enterprise to help with the clean-up operation.

“It’s quite literally like a war zone,” Mr Kemp said. “We’re living to the soundtrack of people sweeping glass.

“It’s been quite extraordinary to see thousands of people descend on the area and help other people as if they were family and clean up other people’s houses.

“The destruction is unimaginable. No house in this area has escaped.”