JERUSALEM — Israel and Hamas were on the brink of war yesterday night as a senior member of the Islamic movement hinted that it would stop observing a 20-month-old cease-fire in retaliation for the latest Israeli assault on the Gaza Strip.

The Israeli military insisted that it would carry on targeting Hamas, after what it described as clear evidence that the movement was smuggling weapons into Gaza to mount cross-border attacks.

After a series of raids by Israel over the last four days in which 22 Palestinian Arabs, mostly Hamas members, died, a minister in the Hamas government, Atef Idwan, said Israel’s offensive showed the cease-fire was effectively over.

“Which is better — to respond to the Israeli aggression or not to respond,” Mr. Idwan, who serves as minister for refugee affairs, asked.

“Which is better — to defend yourself or surrender to the enemy? The ceasefire should be bilateral, but what we see now shows Israel has never committed to a cease-fire.”

A senior Israeli defense official, Amos Gilad, accused Hamas of smuggling weapons into Gaza to try to turn the small scrap of land crowded with 1.4 million Palestinian Arabs into a “second Lebanon.”

“Our policy is clear — we will deploy all our efforts to prevent rocket firings and this contraband,” he said, indicating that this would include “ground and air attacks on terrorists and their infrastructure….Hamas, which is reinforcing itself, constitutes a threat to Israel’s security,” he said. “Our priority is to make it more difficult for the continuation of terrorism.”

The latest deaths happened as Israel mounted armed incursions into Gaza, apparently targeting members of Hamas. The home of one senior Hamas member in the southern Gaza town of Rafah was destroyed in an airstrike, while further north, units of armored Israeli infantry supported by tanks attacked several targets.

Israeli attack helicopters targeted Hamas fighters but several civilians, including at least one woman and three children, died in the crossfire.

Hamas militants have so far responded at a relatively low level, firing homemade Qassam rockets from Gaza into Israel without any reports of injuries.

While this is likely to provoke further Israeli military reaction, it would be far worse if Hamas returned to using suicide bombings as it did during the second intifada of 2000-2005. No such attacks have taken place since the leadership agreed to observe the cease-fire negotiated in February last year.

Mr. Iswan said that, while his side had largely observed the cease-fire, Israel has continued to mount operations against Palestinian Arab targets. “Israel asked others to ask for the ceasefire, but Israel has never stopped its crime against the Palestinian people,” he said. “Israel is beating us badly, that is true, but that does not mean we should not respond.”

Human-rights groups have reported that Israel has killed more than 230 Palestinian Arabs, including scores of civilians, since it launched “Operation Summer Rains” in the summer. Two Israeli soldiers, including one killed by so-called friendly fire, have died in the same period. Israel argues that the large number of Palestinian Arab fatalities resulted from operations it was forced to carry out after the capture of a soldier by Palestinian Arab militants.