Leftist leaders from around the world joined today with Lebanese Moslems and Palestinian commandos to pay tribute to Kamal Jumblatt, the assassinated leader of the leftist Moslem-Palestinian coalition during 19 months of civil war.

The combination of world Socialist solidarity and Arab emotionalism was capped by Palestine Liberation Organization Leader Yasser Arafat, who struggling to control his tears, declared Jumblatt "a martyr of the Palestinian revolution."

Jumblatt was assassinated March 16, and the traditional celebration marking the end of the Moslem 40-day mourning period was postponed for six days so it could be part of the May Day meeting, which commemmorated the anniversary of the founding of Jumblatt's Progressive Socialist Party on May 1, 1949.

The gathering was an attempt by the Moslem leftists, with the help of the Palestinians and world Socialists, to reassert themselves in the Lebanese political scene after the death of Jumblatt.

Even before Jumblatt's assassination, and more so after it. Lebanese politics have been dominated by the Lebanese Front headed by rightist Christian warlords.

The meeting, was designed to thrust Jumblatt's 28-year-old son, Walid, into the party leadership. He was given the starring role as the final speaker at today's rally.

Repeating the philosophy of his father, he called for an end to political and economic sectarianism that has divided the Lebanese people. Under an unwritten law, the minority Christians control the most important government posts and run the country's economy.

But while Walid decried sectarianism, the meeting itself illustrated the tribal nature of Lebanese politics as each leader, accompanied by his bodyguards, entered the hall.

Druze sheiks, dressed in the traditional baggy black pants and high white hats, sat together in the audience, symbolizing Jumblatt's important role in that religious community. Leganese government officials headed by Premier Salem Hoss, a Moslem, sat in the front row.

Arafat linked Jumblatt to the Palestinian revolution and called Walid "my brother."

He pledged that "The Palestinian revolution will continue, will continue, will continue, and the Lebanese nationalists movement will continue to be as giant as always."