President Chaim Herzog asked Prime Minister Yitzhak Shamir on Monday to form Israel's next government, and Shamir pledged to make a "tremendous effort" to advance peace with the Arabs.

The president called on Israel's two major parties, Shamir's right-wing Likud and the rival left-leaning Labor, to try to form a national unity government.But it appeared most likely Shamir would form a government with small right-wing parties and three religious parties.

Shamir, speaking at the presidential mansion after being summoned by Herzog, agreed to try to explore a unity government but made it clear he alone would lead the government and would not share power with Labor as he did after the 1984 stalemated elections.

Shamir promised to include in his Cabinet all the parties "that would agree to be part of a Likud-led government."

However, Labor Party Secretary-General Uzi Bar-Am said Labor would accept nothing less than an equal partnership with Likud.

After the 1984 elections, Shamir and Peres agreed to divide Cabinet posts equally and both served as premier for two years. This time, however, Likud has the ability to form a government with small religious and right-wing parties and was unlikely to grant Labor's demand for equality.

Herzog referred to the growing tension between secular and religious Jews in Israel and the Orthodox and non-Orthodox abroad that emerged after religious parties demanded major concessions as the price for backing Shamir.

Based on thousands of telegrams and letters to his office, the president said, "There is a wish for unity to confront the dangers from outside and the separation threatening us from within."

Ultra-Orthodox parties have demanded legislation giving them final say over conversions to Judaism, marriage and divorce.