Ehud Olmert, the Israeli prime minister, has approved the first shipment of weapons to Mahmoud Abbas, saying this week he wanted to help the president against the Hamas government.
Israel's mass circulation Yedioth Ahronoth daily on Thursday reported that the Jewish state had transferred 950 M-16 rifles from Jordan to Abbas's forces.
Senior Hamas legislator Mushir al-Masri said Hamas was demanding an explanation from Abbas. "Any Israel intervention in our internal affairs is rejected because the Israelis aim to sow divisions among the Palestinian people," he said.
On the same day, Israeli forces shot dead three Palestinian fighters on the border with the Gaza Strip, a Palestinian medical source said.
Witnesses said they belonged to the radical Islamic Jihad group.
An Israel military spokesman said the three were preparing to plant a bomb and all had been killed or wounded.
The Palestinians were intercepted near the former crossing of Kissufim, east of Gaza City, by an elite infantry unit on patrol with air support, the spokesman said.
Abbas' aides have denied reports
of weapons shipment to loyalists
Palestinian ambulances were dispatched to the scene to recover the bodies.
Earlier on Thursday, Israeli army radio reported that four rockets had hit the Israeli town of Sderot, near Gaza.
Medics said two people were lightly wounded.
Responding to the reports of weapons delivery to Abbas's security forces, Saeb Erikat, a Palestinian negotiator and Abbas aide, denied any such shipment.
"[The arms] are waiting in Jordan and have been there for the past six months," he said.
But Yedioth Ahronoth, which did not quote officials, said two trucks escorted by the Israeli army took 400 rifles to the West Bank city of Ramallah, where Abbas has his headquarters.
"Any Israel intervention in our internal affairs is rejected because the Israelis aim to sow divisions among the Palestinian people"
Another 550 guns were taken to the Gaza Strip.
Israeli defence ministry officials could not be reached for comment.
Palestinian officials and Western diplomats have said Jordan and Egypt will provide weapons, ammunition and training for Abbas's presidential guard.
About 20 people have been killed in clashes between Hamas and Abbas loyalists in Gaza in the past month.
Internal Palestinian tensions have also been worsened by a Western aid boycott and banking restrictions.
To circumvent the curbs, Hamas has brought nearly $30 million into Gaza through its border with Egypt in recent weeks.
Palestinian security sources said Youssef Rizqa, the information minister, passed through the Rafah border crossing on Thursday with $2 million in his luggage.
Mahmoud al-Zahar, the foreign minister, brought in suitcases stuffed with $20 million in cash on Wednesday.
Hamas has said the money will be used partly to pay overdue salaries.