With the preliminary final count in Israel's national election showing Prime Minister Menachem Begin's ruling Likud Party and the opposition Labor Party deadlocked at 48 parliamentary seats apiece, the chairman of the National Religious Party called today for another election in one year's time and the formation of a government of national unity to rule until then.

Meanwhile, there were indications from the Begin camp that the prime minister was concerned that he may not be able to form a coalition. One Begin aide said he now expects drawn-out coalition negotiations, and said the key religious parties are likely to raise their terms for joining any government.

Interior Minister Yosef Burg, chairman of the pivotal National Religious Party, said that after a "really cruel and very vicious" election campaign, Israel needs a "cooling-off" period in which Likud, Labor, the Religious Party and the ultraorthodox Agudat Yisrael Party would join forces and govern collectively until another election is held.

There have only been two governments of national unity in Israel's 33-year history and none has ever been formed after an election. In 1967, just before the Six-Day War, the late prime minister Levi Eshkol formed a unity government in which Begin served as minister without portfolio, but it was disbanded the next year. In February 1969, after Eshkol died, Golda Meir set up a unity government including Likud members, but it was dissolved the next year.

The Israeli Elections Commission issued a final, unofficial count of votes today for election to the 120-member Knesset (parliment), and Likud and Labor each won 48 seats. Other seats allotted were: National Religious Party, 6; Agudat Yisrael, 4; Democratic Front for Peach and Equality (a pro-Soviet, communist party), 4; Tami Party, 3; Shinui, 2; Tehiya, 2, and Citizens' Rights Movement and Moshe Dayan's Telem Party, 1 each. The Army vote is expected to decide the 120th seat.

Officials said ballots cast by the armed services will add one seat to either Likud or Labor. The final and official results are not expected until next week.

The new tabulation makes it even more difficult for either Likud or Labor to form a coalition government based on a 61-seat majority, since Agudat Yisrael slipped one seat and Labor dropped one seat from earlier projections. A source close to Begin said that the prime minister, who confidently predicted on Wednesday that he would form a coalition in one week that it may be unattainable.

The Council of Tora Sages, governing body of Agudat Yisrael, was said to have expanded its "shopping list" of demands for Likud concessions before it agrees to join a Begin government.

These now reportedly include: an amendment of the immigration Law of Return to specify that a Jew is either the child of a Jewish mother or one who has been converted according to Orthodox law; stricter legislation on Sabbath work permits; a ban on all sale of pork, even to Gentiles; large increases in state funding of yeshivas (religious schools) and housing for yeshiva students, and tightened laws against abortions and autopies.

Likud sources said Begin had been anxious to get the Agudat and National Religious Party into a coalition quickly, but that both parties realized their potential for increasing their demands and decided to wait longer.

Interior Minister Burg, speaking in an interview on the state radio, said, "I believe after this really cruel and very vicious election campaign, where personal accusations were not lacking, it is quite necessary to have a cooling-off period of one year at least. . . . During this year, there could be political and economic ground acceptable to all the parties -- Likud, the [Labor] Alignment and we. On other issues, a majority would decide, either a majority of the government or the Knesset."

When asked if Labor and Likud could be expected to agree on the question of autonomy for Palestinians in the West Bank and Gaza Strip, Burg replied, "These negotiations are not easy because we cannot give up certain things that belong to the security of Israel." Nevertheless, he said, "I believe in this also we can find a common ground."