GAZA CITY, Gaza Strip — Israeli troops backed by aircraft and tanks clashed with Palestinian militants firing mortars and machine guns near Gaza's former international airport Sunday, killing three gunmen and a civilian, health officials said.

More than 20 people were wounded, including several gunmen and a 45-year-old civilian who lives near the airport and was shot in the head, said Health Ministry official Moaiya Hassanain.

The fighting erupted when Israeli undercover troops took over several homes near the airport in southern Gaza. Israeli tanks and bulldozers moved in to back the troops, and Israeli aircraft struck twice, Hamas said.

In one airstrike, three gunmen were killed, including two from Hamas and one from a smaller militant faction, the Popular Resistance Committees, said Hassanain. A civilian was also killed in the clashes, he said.

The fighting erupted near Gaza's international airport, which was inaugurated in the late 1990s and was largely destroyed by Israel after the outbreak of the second Palestinian uprising in 2000. The airport is close to the border with Israel.

The Israeli military said the operation was aimed at militants who regularly fire rockets and mortars at southern Israel. It said one of the airstrikes was aimed at militants approaching soldiers.

As part of the army raid, bulldozers razed farmlands in an effort to deny rocket squads cover, and the army was carrying out arrest sweeps of men under 45, Hamas security and residents said. According to Hamas, at least 25 men were arrested.

Separately, a Hamas militant died of wounds sustained in an Israeli airstrike last week.

Later Sunday, a Palestinian rocket struck a house in the southern Israeli town of Sderot, shortly after the U.N.'s humanitarian chief condemned the rocket fire and urged Gaza's Hamas rulers to end the attacks. Police said there were no injuries from the rocket strike.

"We condemn absolutely the firing of these rockets. There's no justification for it. They are indiscriminate, there's no military target," John Holmes, the U.N. undersecretary general for humanitarian affairs, told The Associated Press after a tour of Sderot.

Also Sunday, a Palestinian negotiator said that Palestinian President Mahmoud Abbas and Israeli Prime Minister Ehud Olmert would meet Tuesday, as part of Israeli-Palestinian peace talks. The meeting will be held at Olmert's Jerusalem residence, said negotiator Saeb Erekat.

Israeli government spokesman Mark Regev said the date was not firm, but that Abbas and Olmert were trying to arrange a meeting in coming days.

The two sides relaunched talks in November at a peace conference hosted by President Bush, and set a December 2008 target for reaching a final accord. But negotiations have faltered over Israeli settlement activity and daily violence, including attacks on Israelis, rocket fire from the Gaza Strip and retaliatory Israeli military strikes.

Erekat did not confirm an Israeli media report that the two sides have moved closer on deciding the fate of Jerusalem. The Palestinians want to establish their future capital in the eastern sector of the city, which Israel annexed after capturing it in 1967.

"There are talks going on but I wouldn't use the word progress," Erekat said.

Also Sunday, French Foreign Minister Bernard Kouchner met with Israeli President Shimon Peres, following talks the day before with Abbas and Palestinian Prime Minister Salam Fayyad.

Kouchner told Peres that the Palestinians appear increasingly hopeless about establishing a state, according to a statement by Peres' office.

Kouchner noted that no progress has been made in negotiations since the November peace conference. "It is a dangerous thing," he said, according to the statement.