In a surprise move, about 80 Palestinians, including Hamas members and militants from other factions wanted by Israel, crossed from Egypt into the Gaza Strip before dawn on Sunday, according to Hamas and Israeli officials.

The entry, through the closed Rafah crossing on the Gaza-Egypt border, was the result of what Hamas said was an agreement it made with Egypt.

The Rafah crossing was closed in June once Hamas, which many consider to be a terrorist organization, seized control of Gaza, routing rival Fatah forces there. The closure of the crossing was meant in part to prevent militants outside the territory at the time of the Hamas takeover from moving freely into Gaza.

Since the closing, anyone who wanted to enter Gaza from Egypt had to pass through Israeli territory.

The episode had something of a cloak-and-dagger feel, in part because it happened under cover of night and because the stories about who approved the crossing were so vague and conflicting.

News reports quoted Hamas as saying it had reached an agreement with Egypt, and The Associated Press reported that Egypt’s Interior Ministry had confirmed that. But Shlomo Dror, a spokesman for the Israeli government department that oversees the Gaza border crossings, said that Israel had “heard from the Egyptians” that those who crossed Sunday had broken through the fence at the border.

He also said he was unaware of any Israeli green light for Sunday’s border crossing, though he did not discount the possibility of a tacit understanding unknown to his department. The prime minister’s office had no comment.

Among those who crossed into Gaza were Palestinian militants who had been in Iran and other Muslim countries, presumably for military training, according to Mr. Dror. “They are not people we would have been eager to let in,” he said.

The returnees also included members of Islamic Jihad, according to Sami Abu Zuhri, a spokesman for Hamas. Two Hamas legislators, including Mushir al-Masri, a high-profile spokesman for the movement, also re-entered Gaza.

Before the Hamas takeover in Gaza, the crossing had operated, albeit sporadically, by an agreement involving Israel, Egypt, the Palestinian Authority and the European Union, whose monitors were stationed at the crossing to check all those entering the strip.

The European monitors left after the Hamas takeover, as did the Palestinian Authority’s Presidential Guards, who had secured the Palestinian side of the crossing and who are loyal to the authority’s president, Mahmoud Abbas of Fatah. Neither Israel, Egypt nor the Palestinian Authority in the West Bank have appeared eager to reopen the crossing for routine traffic now that Hamas is in charge on the Gaza side.

Mr. Abu Zuhri said that many of those who crossed Sunday were “ordinary citizens.” But Mr. Dror said that Israel had already allowed about 6,000 Gazans who were stranded in Egypt after the Hamas takeover to return to their homes via Israeli territory. Most or all of those who crossed on Sunday are therefore assumed to have feared arrest by Israel.

Egypt played a crucial mediating role in the past between Hamas and its rivals, and is now engaged in a delicate balancing act. Cairo publicly broke ties with Hamas after the Gaza takeover, removing an Egyptian security delegation and diplomatic staff from the strip. But less than two weeks after the takeover, Egypt’s president, Hosni Mubarak, called for a quick resumption of talks to unify the Palestinian factions.

On Sunday, news agencies quoted witnesses who said that the Palestinians had arrived at the border crossing in Egyptian buses and were received by Hamas security men on the other side. Many of them had been stranded for months in El Arish, on the northern Sinai coast.

Mr. Abbas was in Cairo on Sunday for talks with Mr. Mubarak.