Indian Prime Minister Indira Gandhi arrived here today and joined Soviet President Leonid Brezhnev in condemning Israel for last week's massacre of Palestinian civilians and indirectly blaming Washington for having "encouraged" Israel's "criminal aggression" in Lebanon.

An official communique said, "The participants resolutely condemned Israel's criminal aggression -- encouraged from outside -- against the Lebanese, Palestinian and other Arab peoples, its bloody atrocities on Lebanese territory and demanded an immediate and unconditional withdrawal of Israeli troops from Lebanon."

The government news agency Tass, which distributed the communique, later published the text of Brezhnev's message to Chairman Yasser Arafat of the Palestine Liberation Organization in which the Soviet leader described the United States as Israel's "accomplice" -- "the one who armed and encouraged Israel to commit its bloody crimes."

The message continued: "If anyone had any illusions that Washington would support the Arabs or prevent a suppression of the Palestinians after the withdrawal of Palestinian military formations from Beirut -- for this exactly was officially promised by the White House -- now these illusions have dissolved in the streams of blood in the Palestinian camps."

The Soviet leader charged that "the genocide against the Palestinians is the same as that committed by the Hitlerites against other peoples, including the Jewish people, during the Second World War."

Replying to a toast by Brezhnev at a Kremlin dinner, Gandhi talked about Israel continuing its "brazen aggression" in Lebanon and expressed shock at the "massacre of civilians in Beirut." She did not directly blame the Israelis.

Tass, however, said in a dispatch that "the Indian government has accused Israel of the mass murder of Palestinian refugees in Lebanon," and quoted an official Indian statement as saying that "guilt for the tragic events in Lebanon rests also with the United States."

Tass also distributed parts of a message Brezhnev earlier sent to President Reagan. It quoted the Soviet president as proposing joint U.S.-Soviet action in the U.N. Security Council to curb Israel while at the same time accusing the United States of sharing responsibility for the Beirut massacre.

News services reported the following:

In Brussels, the foreign ministers of the 10-member European Community condemned last weekend's massacre of Palestinian civilians, demanded an Israeli withdrawal from Beirut and said the community would support the sending of a new peace-keeping force to the Lebanese capital.

Danish Foreign Minister Uffe Ellemenn-Jensen was authorized to meet with Farouk Kaddoumi, a top official of the Palestine Liberation Organization. Ellemenn-Jensen said at a news conference that the community believed the PLO must be associated with any Middle East peace talks.

Meanwhile, the Qatar news agency said Arab League foreign ministers will convene Tuesday night in Tunis, Tunisia, at the request of the PLO. The meeting, postponed from Monday, will take "effective measures to counter the Israeli enemy," the agency said.

In Damascus, Syria, the Palestine Central Council ended a one-day meeting with a statement blaming the Lebanese Army, the United States, France and Italy for the massacre in Beirut. In the statement the PLO leadership also pledged to avenge the killing of civilians in the camps of Shatila and Sabra.

In Italy, millions of workers went on an hour-long strike and attended rallies denouncing the massacre.The Italian government, which had joined France and the United States in sending a multinational force to oversee the evacuation of Palestinian fighters from West Beirut, issued a communique Sunday expressing its "most firm condemnation and the most angry reproach for the bloody actions that the Israeli Army perpetrated or anyhow consented to and for the tragic slaughter of Palestinian refugees."

Iranian Parliament Speaker Ali Akbar Hashemi Rafsanjani was quoted by Iran's official news agency as saying that although President Reagan condemned the massacre "in fact he was responsible for this crime."

Rafsanjani was also quoted as saying Arab League leaders should have voted an oil embargo against the United States when they met in Morocco earlier this month. "This simple act would have been sufficient to break the world oppression" of Moslems, he reportedly said.

British Prime Minister Margaret Thatcher, on a visit to Japan, issued a statement with Japanese Prime Minister Zenko Suzuki condemning the massacre and saying they would submit a resolution to the United Nations seeking an Israeli pullout from Lebanon.