The Abisan strike inflicted one of the highest tolls from such attacks

Seven Hamas men died in an air strike in southern Gaza and two others were shot near the Gaza-Egypt border.

Hamas officials said the seven men were holding afternoon prayers at a security compound when the missile struck.

The Dimona suicide attack, in which a woman and two bombers died, would be Hamas's first inside Israel since 2004.

However, there remains confusion about the identity of the bombers, after rival groups claimed the attack in the hours afterwards.

Hamas said the attackers came from the West Bank city of Hebron.

Its main militant rival, the al-Aqsa Martyrs, said they had come from Gaza, whose closed border near Rafah was breached on 23 January, prompting Israeli fears of infiltration by Palestinian militants via Egypt.

One of the bombers was injured when his accomplice detonated his bomb in what appeared to have been intended as a co-ordinated attack.

An Israeli army spokesman said Tuesday's air strike in Abisan, near Rafah, was in response to rocket attacks that hit the southern Israeli town of Sderot earlier.

More rockets followed the air strike, and Hamas vowed to take further action.

"This blood will not be shed in vain; this crime will not go unanswered and the Israeli occupation will pay a heavy price," Sami Abu Zuhri said in remarks quoted by AFP.

Hamas - de facto controllers of Gaza - oppose Palestinian Authority President Mahmoud Abbas's peace talks with Israel.

Top Israeli and Palestinian negotiators who met after the Dimona bombing said their efforts would continue regardless of the attack.

Meanwhile, a senior member of Israeli Prime Minister Ehud Olmert's Kadima party, Tzachi Hanegbi, urged the government to revive the tactic of assassinating Hamas political leaders, in addition to strikes against armed elements.

Israel is on high alert after Monday's bombing, with special emphasis on the long and unmarked desert border with Egypt.