Nine Palestinians, including two children, have been killed and up to 20 others hurt in an Israeli air strike in Gaza, witnesses and doctors say.

The Israeli army confirmed the attack, saying it had targeted "a car that was heading to fire rockets at Israel".

The Islamic Jihad militant group said some of its members died in the blast.

Rockets have been fired regularly from Gaza into Israel in recent weeks. Israel has also launched numerous air strikes aimed at Palestinian militants.

The BBC's Alan Johnston in Gaza says although Israeli strikes on vehicles traveling through the territory have become familiar, this is one of the heaviest death tolls from such an attack.

A BBC reporter counted eight bodies being taken to a morgue, including that of a child. Palestinian sources said a second child was also killed.

The exchange of missile attacks between Gaza and Israel has been gathering momentum in recent days, following the deaths of eight Palestinians on a beach in Gaza.

After those deaths, the militant group Hamas, which heads the Palestinian government, said it was breaking off its voluntary truce and launched rockets at Israel.

The beach explosion was initially blamed on Israeli shelling near the area where a family was enjoying a picnic.

However, an Israeli military inquiry is close to deciding Israel was not responsible, media reports say.