Jerusalem — If Israel's border disputes with Egypt are not resolved by April 25, Israel still would be prepared to withdraw its forces and set a new boundary where Israel wants it until mediation can settle the problem.
This would mean Israeli withdrawal from virtually all of the eastern third of Sinai by midnight April 25, as planned.
''We very much would like to have it all worked out and start with a clean slate after April 25,'' a high-level Israeli official said April 18. ''It is not good to begin a new era with Egypt with border problems.''
The Israeli Army was poised April 18 to begin the final evacuation of 3,000 holdout settlers in the northern Sinai city of Yamit. Indications over the weekend were that some Jewish extremists were prepared for violJnt resistance. But Army officials say the evacuation can still be completed in a day or two.
[The Israeli government has begun a bizarre debate with extremists who are threatening suicide if northern Sinai is handed back to Egypt April 25, Reuters reports. The extremists are barricaded in an underground bunker and say they will gas themselves if Israel carries through its pledge to evacuate the territory.
[The government brought in two leading rabbis April 18 to try to persuade the group that suicide would be against the Jewish faith and the teachings of the Bible. Other rabbis who oppose the withdrawal from Sinai argued that in special circumstances suicide was permissible.]
The apparent willingness to go ahead with the removal of the holdouts indicates the Israeli government is taking the steps necessary to meet the midnight April 25 deadline for vacating the territory.
There is considerable optimism among Israeli leaders and diplomats here that most of the outstanding differences between Egypt and Israel over the Sinai can be worked out prior to the handover of the territory to Egypt.
''The fact that we are talking about the matters puts us ahead,'' a Foreign Ministry official said. ''Both sides have a desire to work the problems out, but it is important that no side lose face.''
The problems are in three areas:
* Military: Israel claims Egypt has violated the military annexes to the Camp David accord by stationing too many troops on the east side of the Suez Canal.
* Political: Israel claims Egypt has been aiding the Palestine Liberation Organization and making diplomatic noises that run counter to the spirit of Camp David.
* Geographical: There are some 15 points of dispute along the future border, ranging from arguments over several meters of desert to the problem of whose territory a new Israeli resort hotel at Wadi Taba on the Gulf of Aqaba is in.
Over the weekend, Egyptian Minister of State for Foreign Affairs Butros Ghali delivered a message to Prime Minister Menachem Begin from Egyptian President Hosni Mubarak. It reportedly indicated Egypt was not about to alter its course of peace with Israel.
Egyptian Foreign Minister Kamal Hassan Ali arrives in Tel Aviv April 19 to discuss the problems further. Meanwhile, Deputy US Secretary of State Walter Stoessel was due back in Tel Aviv after weekend meetings with Egyptian leaders on the same subjects.
The Egyptian news agency said April 17 that reports by American observers in the Sinai prove Egypt is not violating the military restrictions it is under in the Sinai. The Israeli Air Force was scheduled to photograph the area (without flying over Egyptian air space) April 18 to verify the Egyptian claim. Egypt reportedly is investigating allegations of Egyptian complicity in PLO arms smuggling into Gaza.
The toughest problems seem to involve exact demarcation of the new border. Egypt is sensitive about compromising on any of the territorial issues because of criticism it might receive from the Arab world for bargaining away part of Palestine.
An Israeli official, however, says such sensitivity shows Egypt is paying too much attention to ''the arguments of Iraq, Syria, and other radical Arabs who don't accept the motion of peace with Israel at all.''
''Egypt must not care for what they say,'' the official says. ''They don't accept the existence of Israel, so a few meters here and there do not matter. They say Tel Aviv is Arab territory.''
Mr. Begin has suggested that Egypt, Israel, and the United States issue a declaration expressing continuing support for Camp David. Egypt has shunned the idea, saying Camp David already has full Egyptian support.
Many Israeli intellectuals are arguing that Israel must not appear too aggressive in its negotiations with Egypt. Their feelings were echoed by the April 18 Jerusalem Post: ''The cause of peace will be genuinely served by getting down to brass tacks - and at this very moment, by disposing, quietly and without fanfare, of such obstacles as last week seemed to imperil the carrying out of Israel's undertaking to vacate the rest of Sinai by April 26.''