Syrian leader Hafez Assad and Soviet President Konstantin Chernenko, met today in the Kremlin and denounced the United States and Israel for "whipping up tension" in the Middle East.

In a statement issued by the Soviet news agency Tass, the two leaders called for the unconditional withdrawal of Israeli troops from Lebanon and stressed the "key importance of a solution of the Palestinian problem" in the Middle East.

Assad's working visit comes at a time when Moscow is stepping up its diplomatic activity in the Middle East, apparently to take advantage of U.S. reversals in the region. Last week, the Soviet Union signed a 20-year friendship and cooperation treaty with North Yemen, a moderate Arab state with strong ties to Saudi Arabia. In the last two months, Moscow has also agreed to exchange ambassadors with Egypt, for the first time since 1977, and sell arms to Kuwait.

Tass announced today that Iraqi Foreign Affairs Minister Tariq Aziz will be in Moscow later this month and, according to Arab diplomats, other Arab officials -- including Jordan's King Hussein -- are expected to pay visits here soon.

The visit by Assad, Moscow's key Middle East ally, has been relatively low-key. It is his first visit since 1980, when the two nations signed a 20-year friendship and cooperation treaty.

The Soviet Union's Middle East initiatives could present problems for Syria, particularly when they conflict with Syria's own policies toward its neighbors, diplomats say. At the same time, Syria's interests are crucial to the Soviet Union, which does not want to alienate a longstanding ally.

Assad was expected to raise several sensitive issues in his talks with Soviet leaders, including his concern about the recent meeting in East Berlin between Soviet Foreign Minister Andrei Gromyko and Yasser Arafat, leader of the Palestine Liberation Organization. Arafat's PLO leadership has been openly opposed by Assad, who backed anti-Arafat rebels during the fighting in Lebanon earlier this year.

The Soviets in the past have expressed displeasure at rifts among its Arab allies. During a visit here last year by Syrian Foreign Minister Abdul Halim Khaddam, Gromyko openly admonished factions in the PLO to end the infighting.