BEIRUT, NOV. 8 -- The Abu Nidal terrorist organization said today it had seized a 40-foot boat and taken captive eight Israelis aboard, including two children. There was no independent confirmation of the incident.

Walid Khaled, described as a leader of the organization, told a news conference in the Moslem sector of the Lebanese capital that a seaborne unit had seized the group off the Israeli-occupied Gaza Strip.

Khaled said the hostages were being detained at one of Abu Nidal's bases, without specifying the location. He did not give the date of the seizure.

Khaled said the eight were being interrogated after receiving "proper medical care and humanitarian treatment." The group offered to show the eight to a representative of the Red Cross.

The timing for publicizing the alleged seizure of the French-registered, 17-ton Silco apparently was related to the Arab summit that opened today in Amman, Jordan, to discuss the Iran-Iraq war and the Arab-Israeli conflict. Khaled warned the Arab leaders not to support "Jordanian King Hussein's call to negotiate on behalf of the {Israeli-occupied} West Bank" in talks Hussein has advocated with Israel.

Khaled identified the passengers on board as five people carrying dual Israeli and Belgian nationality, one with dual Israeli and French nationality and two Hebrew-speaking little girls. However, the passport numbers given were of travel documents issued by the Belgian consulates in Marseilles and Lyon in France as well as French authorities. No evidence was produced proving the eight were Israelis.

{Spokesmen for the Israeli, Belgian and French governments all disclaimed any knowledge of the incident, news services reported.}

Khaled said a unit was on a mission to support the "armed popular uprising inside Palestine" when it ran into the Israeli party.

The Abu Nidal representative faced journalists in a rare public appearance for guerrilla officials of his level, meeting the press at the once-fashionable Carlton Hotel.

"After successfully completing its mission and attempting to leave the shores of Gaza, one of our unit's vessels collided with a Zionist boat flying the Israeli and Belgian flags," Khaled said. He warned Israel not to risk any retaliatory action against Palestinian camps.

Israeli warplanes have carried out 22 air raids against Palestinian targets in Lebanon this year. On Sept. 5, 20 of Abu Nidal's followers were reported killed in one such raid.

Closure of Abu Nidal's office in Damascus earlier this year was welcomed by Washington and resulted in the return to the Syrian capital of Ambassador William Eagleton after an absence of 11 months. He was withdrawn following international indignation over Syria's suspected role in world terrorism and its support to leaders such as Abu Nidal.

Abu Nidal has made no secret of maintaining military bases in Palestinian camps in central and southern Lebanon as well as representatives in Beirut. There are about 7,000 Syrian troops in Beirut.

The Moslem western half of Beirut, where the press conference was held, is policed by Syrian soldiers and a growing network of Syrian intelligence agents. It is believed that the terrorist group, going by the name of the Fatah Revolutionary Council, is believed to receive backing and financial support from Libya.

Abu Nidal followers have bases in the Ain Helweh camp east of Sidon and the Syrian-held Bekaa Valley in central Lebanon. The group is believed to have carried out bloody attacks in Rome and on a synogogue in Istanbul, Turkey, as well as a hijacking in Pakistan last year.