Israeli troops killed a Palestinian militant and a teenager on Thursday during a raid into the occupied West Bank, a day after 17 Palestinians, most of them civilians, and three Israeli soldiers, were killed in the Hamas-controlled Gaza Strip.

Palestinian medical and security officials said the militant, a member of Islamic Jihad, and the 16-year-old youth were shot by soldiers who surrounded a house where gunmen were believed to have been hiding in Qabatiya refugee camp near the city of Jenin.

An Israeli army spokeswoman said troops fired at militants after they refused to exit a vehicle parked in the house’s driveway.

The incident followed the bloodiest day in over a month in the Gaza Strip, when three Israeli soldiers were killed and three injured in an ambush by Palestinian gunmen from Hamas, the Islamist group, during an Israeli raid into the Gaza Strip.

It was the highest toll suffered in a day by Israel’s armed forces since the 2006 Lebanon war, and means seven soldiers have been killed this year, more than the whole of 2007.

The fighting claimed the lives of four Hamas gunmen. Later in the day a series of Israeli air strikes killed at least a dozen more Palestinians, including several children and a cameraman working for the Reuters news agency.

A medical examination showed on Thursday that metal darts from an Israeli tank shell that explodes in the air caused the death of the cameraman, doctors said.

X-rays displayed by physicians who examined the body of Fadel Shana in Gaza’s Shifa hospital showed several of the controversial weapons, known as flechettes, embedded in the 23-year-old Palestinian’s chest and legs.

Asked about the information that an Israeli flechette shell had killed Shana, an Israeli military spokeswoman told Reuters: ”The Israel Defence Forces do not, as a rule, comment on the weapons they use. But its weapons are legal under international law.

”Flechettes are legal under international law and a petition filed in the (Israeli) Supreme Court against their use was rejected,” she added.

Wednesday saw a sharp increase in rockets launched by Gaza-based militants on nearby Israeli towns.

According to the army and reports from the Gaza Strip, the soldiers from Israel’s Givati Brigade entered the southern part of the Hamas-controlled territory to pursue several Palestinian fighters. Once inside, the soldiers came under attack from gunfire and rocket-propelled grenades. Hamas claimed responsibility for the attack.

Wednesday’s ambush – and the rising number of Israeli military casualties – provides further evidence of the growing military prowess of Hamas and other Gaza-based militant groups. This year they have not only targeted Israeli towns with rockets and mortars, but have also launched well-planned and brazen attacks on Israeli soldiers and civilians.

Last week a group of fighters broke out of the territory to attack a fuel depot on the Israeli side of the fence surrounding Gaza, killing two Israeli workers. Last month Palestinian militants detonated an explosive charge as an Israeli military jeep drove by, killing one soldier and injuring three more.

A report released last week by an Israeli group called the Intelligence and Terrorism Information Centre said Hamas had accelerated its military build-up over the past year, using Hizbollah, the Lebanese Shia militia, as its role model. It claimed the Islamist group had 20,000 fighters and an increasingly modern arsenal of weaponry.

Hamas also had “improved capabilities to carry out complex terrorist attacks such as mass-casualty attacks and the abductions of soldiers and civilians”.

Wednesday’s violence came as Jimmy Carter, the former US president, was due to meet two senior Hamas leaders in Cairo, the Egyptian capital. The meeting has drawn criticism from both Israeli and US politicians, but Mr Carter argues the group’s backing will be crucial for a peace deal.