Israeli aircraft have bombed a building in the Gaza Strip, which it said concealed an entrance to a tunnel used by Palestinians to carry out cross-border attacks.

Witnesses said that the building was destroyed by the attack early on Sunday, but there were no casualties.

An Israeli military spokesman said the raid was in response to a rocket fired from Gaza into Israel on Saturday, which caused no damage.

"The building was located 1.5 km from the border and concealed a tunnel that was to have been used by terrorists to infiltrate Israel for an attack," the spokesman said.

Hamas, which controls the Gaza Strip, described the target as "open ground" but witnesses said it was a building with two rooms and a courtyard.

An Israeli security source said intelligence indicated the tunnel had been dug by several Palestinian factions other than Hamas.

Gaza explosions

Earlier on Sunday, Hamas said that unidentified Palestinians had set off explosive devices at two of its security compounds in Gaza City.

Hamas said the attacks had targeted the Ansar-2 security compound and the Gaza residence of Mahmoud Abbas, the Palestinian president, who has stayed away from the territory since his Fatah faction was forced out by Hamas in 2007.

Hamas security sources said that they had defused a third bomb near what is known as the department for security and protection.

No one claimed responsibility for the attacks, while Israeli military sources denied involvement.

Ihab Ghussein, Hamas interior ministry spokesman, said they were investigating the explosions.