Jonathan Steele in Beirut

Heavily bandaged with only his eyes and mouth showing, 18-year-old Zakaria Alamedin lies in a Beirut hospital, still unaware that his father died in the rocket attack which burnt his face.

He was lucky to have just left the cellar of the 14-storey office and apartment block where most of his family were sheltering in the city of Tyre. Someone had phoned to say Hassan Nasrallah, the Hizbullah leader, was on TV and he ran upstairs to watch. It saved his life.

The Israeli bomb left the tall building standing but homed in on the basement which is open at one side. Twenty people who had thought they were safe died instantly. Forty were wounded.

In Beirut’s city centre Isam Kaoun, a 31-year-old house-painter, tells a similar story of mass death. He was in his home town of Srifa last week when Israeli missiles struck three houses in rapid succession shortly after 3am. They killed nine people in one basement shelter, six in another, and six in a third.

While Israeli missiles continue to strike vehicles full of desperate refugees fleeing their villages in south Lebanon, Israel is also accused of targeting a large number of homes and office buildings used only by civilians.

Researchers for Human Rights Watch, the New York-based non-governmental organisation, say they have compiled details on the deaths of more than a quarter of the roughly 400 Lebanese killed by the air strikes Israel launched a fortnight ago. “We’ve investigated the results of air campaigns in Kosovo, Afghanistan, and Iraq, and the pattern here is different. They’re hitting civilians time and time again,” Peter Bouckaert, a long-serving Human Rights Watch investigator, said.

“Just because the Israelis are using smart weapons doesn’t mean they’re hitting military targets,” he added. “The Israelis seem to make no discrimination between military and civilian targets.”

In many cases the Israeli attacks have killed or injured entire families. Ahmed Ali, a taxi driver, 45, lies in a room at Beirut’s Rafik Hariri hospital. He has lost both his legs. In a room nearby sits his wounded wife, Akram Ibrahim, cradling their one-year-old daughter with a bandage on her tiny right arm. Ten-year-old Ali Ahmed Ali is in a wheelchair, his body peppered with blood-stained injuries.

They lived in Blida, a village of 3,500 less than a mile from Lebanon’s eastern border with Israel. “We woke at 6.30am last Wednesday to the sound of a bomb exploding somewhere else in the village. So we rushed down to the basement and waited until the heavy bombing ended,” said Akram Ibrahim.

“At 2.30pm they started again and we went down again. There were 12 people in the cellar. It’s an ordinary house, nothing special. Then we were hit.” Hundreds of people from Blida have now fled, but 200 remain there in fear.

The Human Rights Watch researchers are convinced from Ahmed Ali’s description that the family was injured by at least two cluster bomblets, which entered the basement, releasing metal fragments. The weapons are a standard part of Israel’s arsenal and were used by them in Lebanon in the 1980s.

A separate team of Human Rights Watch investigators photographed cluster munitions with Israeli forces near the Lebanese border in recent days. The photographs show M483A1 “dual purpose improved conventional munitions”, which are produced in the United States.

“Our prior research in Iraq and Kosovo clearly shows that cluster munitions cannot be used in populated areas without huge loss of civilian life. Human Rights Watch calls upon the Israeli military to immediately cease the use of indiscriminate weapons like cluster munitions in Lebanon,” Mr Bouckaert said.

In Srifa, an inland town of about 10,000 people, the Israeli attacks have been particularly lethal, killing as many as 42 people, according to Human Rights Watch. Jan Egeland, the United Nations humanitarian affairs coordinator, was visibly shocked after meeting Srifa survivors in Beirut yesterday. He called for access to be opened to the inland villages.

“We hear horrific stories from there where so many women and children were killed. The women told us ‘Let us at least be able to retrieve our bodies, because the dogs are eating them’,” he said.