The Israeli army has promised a “lengthy” offensive against Hamas, after a fresh wave of airstrikes against Gaza and a salvo of dozens of rockets fired from the strip into southern Israel.

Palestinians told Al Jazeera that eight people were injured in the Israeli strikes on Tuesday morning, one of which reportedly targeted the house of a senior member of the Qassam Brigades, the military wing of Hamas.

The bombings came after at least 20 rockets were fired from Gaza. No injuries or damage were reported.

Overnight, the air force carried out some 50 airstrikes in the besieged territory, and on Tuesday Moshe Ya’alon, the defence minister, said the current campaign in Gaza would be lengthy.

"We are preparing a campaign against Hamas that will not be completed within a few days," Ya’alon said. "We are prepared to expand the campaign using every means at our disposal, to continue to strike the terrorist organisation."

Prime Minister Benjamin Netanyahu has so far resisted pressure from within his government to launch a major offensive. But on Tuesday he said Israel would "take the gloves off" in dealing with Hamas.

"[They] chose escalation, and will pay a heavy price."

The army announced on Tuesday that it will also mobilise "several thousand" more reservists, on top of 1,500 called up the previous day.

An army spokesman said that "all options are on the table," provoking speculation that a ground invasion is being considered, but so far there is limited support for that within the government.

Vow to respond

The Islamic Jihad group has claimed responsibility for most of the rockets fired over the past few weeks.

On Monday night, though, for the first time in the current fighting, the Qassam Brigades took credit for a barrage. The group has vowed to respond for a series of Israeli strikes on Sunday night, which reportedly killed seven of their fighters.

Hamas-affiliated media claimed on Tuesday that the group had fired a surface-to-air missile at Israeli jets, though that could not be independently confirmed.

Moussa Abu Marzouq, a senior member of Hamas, promised "ongoing resistance until we have victory," saying in a statement that Hamas "will make this a lesson that history will not forget."

Egyptian-led efforts at mediating between Hamas and Israel have so far been unsuccessful. Sources in Gaza told Al Jazeera that Hamas has demanded an easing of the blockade as a condition for stopping the rocket fire.