Israel reopened three of its border crossings with the Hamas-ruled Gaza Strip on Sunday following a halt to Palestinian cross-border shelling attacks that had strained an Egyptian-brokered truce, officials said.

An Israeli military spokesman said Sufa commercial crossing, the Nahal Oz fuel-transfer deport and the Erez border terminal for travelers resumed operations at 8 a.m. (0500 GMT), with some restrictions in force.

Another commercial crossing, Karni, remained closed. Peter Lerner, an Israeli defense official, cited a policy decision for the closure but did not elaborate.

Israel shut the crossings on Wednesday after an Islamic Jihad rocket salvo which the Palestinian faction called retaliation for Israel's killing of one of its West Bank chiefs. Other Gazan militants fired a rocket and two mortar bombs in two separate incidents. There were no Israeli casualties.

The truce, which began on June 19, calls for Hamas to stop cross-border rocket fire and for Israel to gradually ease its embargo on Gaza. It does not apply to the West Bank.

Hamas, which has stuck to the truce, called last week for smaller Palestinian factions to abide by the ceasefire and said it would take "necessary measures" against violators.

An official of al-Aqsa Martyrs Brigades, a militant group that fired into Israel last week despite the truce, said Hamas security forces arrested its senior spokesman, Abu Qusai. Hamas security officials were not immediately available for comment.

He was later released after being held for about 10 hours.

Abu Qusai had claimed responsibility on behalf of the group, which belongs to Palestinian President Mahmoud Abbas's Fatah faction, for a rocket strike it described as retaliation for Israeli raids in the West Bank.

Hamas accused Israel of foot-dragging.

"Movement across the commercial crossings is still very slow and there has been no change at all, at least as of this moment," Hamas official Sami Abu Zuhri said.

"Commitment to the 'calm' deal by Hamas and other factions was conditional on the price the occupation must pay in return," he said, referring to Israel.

Lerner said 80 truckloads of goods would be allowed across Sufa, up from the daily average of around 60 trucks before the truce. Israel on Friday allowed fuel to reach Gaza's sole power station through Nahal Oz.

Israel sharply cut back on the supply of goods into the Gaza Strip a year ago, after the Islamist group Hamas took over the coastal enclave from forces loyal to Palestinian President Mahmoud Abbas's more secular, Western-backed Fatah faction.

There is a third commercial crossing on the Israel-Gaza border, Kerem Shalom, but it has been closed since a Hamas bomb and gun attack on April 19.