Italian and Austrian officials investigating last Friday's simultaneous attacks on the Rome and Vienna airports have concluded that the seven terrorists known to be involved were all part of an organization headed by Palestinian renegade Abu Nidal and were trained outside of Beirut, according to officials here.

Those conclusions, according to the sources, resulted from a meeting last night and early today in Vienna between Italian and Austrian police and judicial officials to coordinate investigations of the attacks that left 18 persons dead and more than 100 wounded.

In another development, Italy's Foreign Ministry called in the Libyan ambassador to protest a characterization by the official JANA news agency of the attacks as "heroic missions." Yesterday, Prime Minister Bettino Craxi denounced the JANA statement as the expression of "a bloody and fanatic faith."

[The Libyan Foreign Ministry sought to distance Libyan leader Col. Muammar Qaddafi from Sunday's JANA account, United Press International reported. The statement over Libyan radio, monitored in London, added that U.S. and Israeli statements on the attacks provided evidence of plans for "joint aggression" against Libya.]

In a telephone conversation with Craxi yesterday, Tunisian Prime Minister Mohammed Mzali relayed evidence that two Tunisian identity cards associated with the terrorists in Rome had been taken from Tunisian citizens while they were guest workers in neighboring Libya. A third reportedly had been lost by its owner in Libya almost 10 years earlier.

According to sources close to Craxi, the Tunisian charged that the Libyan secret services had in their possession "hundreds" of Tunisian passports and identity cards confiscated from Tunisian workers before all 32,000 of them were expelled from Libya last fall after Tunisia broke off diplomatic relations because of border tensions.

Italian official sources close to investigating magistrate Domenico Sica said today after his return from Vienna that it was now agreed that the label "Martyrs of Palestine," used to identify the Rome attackers in a note found on the sole surviving assailant here, simply was chosen by Abu Nidal's organization to cover the joint operation.

The Italian sources said Mohammed Sarham, the lone survivor of the four who attacked at Leonardo da Vinci airport, has admitted that the Martyrs of Palestine was headed by Abu Nidal and they now suspected the group was just a front for his Fatah -- Revolutionary Command.

According to these sources all seven of the terrorists in the two attacks trained together in November at a secret camp somewhere outside of Beirut, then were sent to Europe. They said evidence indicated some flew to Athens, others to West Germany and at least one to Geneva.

A spokesman for the prosecutor general's office in Zurich confirmed that one member of the team that attacked in Vienna had passed through Switzerland but said "there was no evidence that there was an operational base in Switzerland."

The Italian sources said Italian and Austrian investigators believe that some or all of the terrorists made their way to Switzerland, where instructions and cash were handed out for the two operations. The Rome group, by this account, arrived here by train at the end of November.

Apparently the terrorists entered Italy without the guns and grenades they were later to use in their attack. These, according to Italian sources, must have been supplied by a back-up team suspected of running an "operation center" for such attacks in and around Rome.

President Francesco Cossiga said Italy and Austria "have always shown great understanding for the people who fight for their freedom and independence, including the Palestinians.

"Also for this reason, the incredible acts of violence gave us profound bitterness," Cossiga said in a year-end statement. "As citizens of a civilized nation, our condemnation is the strongest, without appeal, without reservation."

United Press International, in its report from London, added:

The Libyan Foreign Ministry said, "The biased imperialist western media have rushed to involve the name of the brother commander of the revolution [Qaddafi] in a statement issued by a news agency which deals in events and news just like any other news agency in the world."

The statement said Libya "denounces and rejects every action that harms the innocent." But it said world opinion should bear in mind that international disregard for the Palestinian cause "prompts those whose cause it is to the most violent methods."

The statement, monitored by the British Broadcasting Corp., also criticized anti-Libyan statements by the U.S. State Department and the Israeli prime minister, saying they were evidence of plans for "joint aggression against the Jamahiriyah [Libya] by the American military machine and Israel."

The Libyan representation in Vienna issued a statement denying a Tripoli role in the attack and a spokesman for the Libyan mission in Rome said reports of Libyan involvement were "false."