JIDDAH, SAUDI ARABIA, OCT. 12 -- The speaker of Egypt's parliament, a close political ally of President Hosni Mubarak, was assassinated today along with four security men when his limousine was ambushed in downtown Cairo by four assailants with machine guns.

Rifaat Mahgoub, 64, was struck in the head by several bullets just outside the Semiramis Hotel shortly before 11 a.m. as he was on his way to an official function at another hotel, police said. Investigators later found two suitcases containing time bombs, hand grenades, detonators and loaded automatic weapons "at the assassination site," an Interior Ministry statement said.

Officials were conducting house-to-house searches in the Cairo neighborhood of Boulaq in an attempt to find the gunmen, police sources told the Reuter news agency.

The slaying of Mahgoub, a prominent member of Egypt's ruling National Democratic Party and constitutionally next in line to Mubarak for the presidency, follows recent accusations by Mubarak that Iraq has sent saboteurs to provoke chaos in Egypt in retaliation for its stand against Iraq's invasion of Kuwait and its decision to send troops to join the U.S.-led multinational force in Saudi Arabia.

But with Mahgoub's killers still at large, Egyptian officials today were reluctant to assign blame for the slaying, and they left open the possibility that it was carried out by violent Egyptian Islamic groups seeking the overthrow of Mubarak's government.

"It could be outside terrorist forces, or it could be our brother {Islamic} groups," said Interior Minister Muhammad Abdel Halim Moussa in an impromptu press conference shortly after the slayings.

In a statement deploring today's killings, Mubarak said that "a crime against Islam has been committed."

In recent weeks, according to local press accounts, Egyptian security officials have arrested a number of Iraqis and Palestinians who they say entered the country -- sometimes using Egyptian and Kuwaiti passports stolen in Kuwait -- to commit acts of terrorism against public officials and tourist sites. Egyptian authorities said they have recently tightened security at public places and points of entry into the country.

The assailants apparently waited for Mahgoub's car under one of the nearby bridges over the Nile and hid their weapons in hand-carried bags, Moussa said. Mahgoub's "bodyguards returned {the gunmen's} fire; however, they were able to escape in a car and a motorcycle," the Interior Ministry statement said. "Two plainclothes policemen chased the gunmen a half-mile" to the nearby Ramses Hilton Hotel where the officers were wounded in a gunbattle with the assailants, the statement added. One of the wounded officers, a police brigadier, later died, officials said.

Moussa said Mahgoub was on his way to meet a Syrian parliamentary delegation at the Meridien Hotel when he was slain. The minister said that two of the four attackers, described as in their 20s and wearing Western-style clothes, fired at Mahgoub and his guards.

If the assassination proves to be the work of pro-Iraqi agents, it is likely to further inflame Egyptian public opinion against Iraqi leader Saddam Hussein. Egyptians have been incensed by Iraqi treatment of Egyptians in Kuwait. An Iraqi role in Mahgoub's slaying would probably also harden Egypt's commitment to the international effort to contain Iraq and reverse its occupation of Kuwait.

"We must get rid of" Saddam, one Egyptian military official said. "We don't need people like him in the region."

But analysts said that even if it is shown that Iraq had a hand in the killings, Egypt is unlikely to retaliate in kind -- partly because it has built its international diplomacy and its efforts to resolve Middle East conflicts on rejection of terrorism, and partly because Iraq's internal security makes it extremely difficult to carry out sabotage there. In addition, Egypt has more than a million citizens working in Iraq who could be victims of Iraqi retaliation.

In a speech six days agao, Mubarak accused Iraq of mounting terrorist actions against Egypt. "Iraq is pushing forces to create a state of instability for us, strike at some institutions, throw some bombs and use arms to attack buses," he said. "I will stand firmly against anyone who tries to tamper with Egypt's stability and security, whatever his nationality, no matter what consequences may follow," he added.

In an interview last week with the Egyptian political magazine Al Mussawar, Moussa spoke of 12 "pro-Iraqi" agents recently arrested, but other local press accounts said that as many as 30 have been detained.

Moussa told the magazine that four different groups planning sabotage against tourist sites were identified as belonging to a group led by the Palestinian terrorist Abu Nidal and including two Palestinians living in Egypt. Abu Nidal, who once was based in Libya, moved to Baghdad several months ago, according to published accounts.

The interior minister said that seven others arrested included Palestinians and Iraqis who had infiltrated Egypt to carry out terrorist acts in Egypt's Sinai desert, whose Red Sea beach facilities are popular among tourists. These were part of the group that attacked a tour bus full of Israeli tourists last February, killing nine of the passengers, Moussa said.

The semi-official Al Ahram newspaper today quoted Moussa as saying that 15 Iraqis and Palestinians arrested last week confessed that they had instructions to attack Egyptian public figures and tourist facilities and were found with explosives and hand grenades. Islamic fundamentalist groups, who want Egypt to be run by religious leaders and to apply strict Islamic cultural codes, have used violence against Egyptian public figures in the past. In 1981, they assassinated President Anwar Sadat, and in 1987 they attempted to kill two former interior ministers.

Since Moussa was appointed interior minister last February, these underground groups have carried out a number of violent attacks against policemen. Last spring, they instigated anti-Christian rioting in several rural villages in southern Egypt.

Diplomatic observers based in Cairo have noted, however, that these groups have been relatively quiet on the issue of Egypt's stand against Iraq's invasion of Kuwait. In part, this may reflect ambivalence about one Arab country invading another, but it also may stem from their awareness that the Egyptian public has been strongly supportive of Mubarak's anti-Iraq position, these diplomats said.