Israel urged Egypt Monday to clamp down on extremists after a lone gunman crossed the lightly patrolled frontier and killed four Israelis in a roadside ambush before being shot and retreating into Egypt.

"We cannot grow accustomed to enduring a peace with Israeli bloodshed," said Israeli Foreign Minister David Levy."The Egyptian government must understand that everything must be done to end this serious situation, which is intolerable. Israeli blood cannot be cheap in Egypt," he said on Israel radio.

Twenty-seven people were wounded in Sunday's attack, which occurred about 15 miles north of Eilat and was among the worst ever along the border.

The attacker sprayed fire from a Kalashnikov automatic rifle into a bus and three military vehicles before he was himself shot and fled, officials said.

A Moslem fundamentalist group called Islamic Holy War-Jerusalem claimed responsibility.

Egypt signed a peace treaty with Israel in 1979, but there have been periodic border incidents. The last attack was on Feb. 4 when gunmen ambushed an Israeli tour bus in Egypt, killing nine Israelis and wounding 20.

Despite strong Israeli concerns about the violence, a top Israeli army official said there are no plans to reinforce Israel's most peaceful frontier.

"The Egyptian border is different than the others . . . it is a border of peace, and I suggest we don't make the mistake of relating to this border as a hot one at war, it would be a real mistake, a psychological mistake," said Chief of Staff Lt. Gen. Dan Shomron on Israel television Sunday.

It was the third attack against Israelis in two days.