Secretary of State Alexander M. Haig Jr. said today the United States plans to speed up arms delivery to Egypt and Sudan and organize a "highly increased U.S. presence in the area" to meet security concerns intensified by the assassination of president Anwar Sadat.

The measures represent a major part of the Reagan administration's response to fears of instability in Egypt and its neighbors caused by the loss of Sadat's leadership and what Haig repeatedly has described as Libyan "manipulation" of forces in Egypt and Sudan hostile to Sadat's peace with Israel and friendship with the United States.

"I think all of this underlines the need for the United States to demonstrate its continuing support for the government and people of Egypt," Haig said on Meet the Press (NBC,WRC), broadcast from Cairo. "We've done so and we're going to do so in more concrete terms in the very near future."

Two other high Reagan administration officials, presidential counselor Edwin Meese III and national security adviser Richard V. Allen, also spoke of stepped-up U.S. military activities in the Middle East. Details on Page A25.

Confirming reports published in The Washington Post, Haig said strong consideration also is being given to dispatching a number of B52 bombers to Egypt temporarily.

A high State Department official said the bombers would make practice runs on Egyptian target fields while underlining U.S. presence here. This would be in addition to the expansion of a long-planned joint military exercise next month including forces of the Persian Gulf sultanate of Oman along with those of the United States and Egypt. The official also mentioned the supply of more arms to Sudan in what he called "emergency action."

The administration plans outlined by Haig suggested U.S. officials have concluded the best immediate response to Sadat's assassination is a demonstration that governments friendly to the United States can count on it for military support. This is particularly true in Egypt, where President-designate Hosni Mubarak is believed to desire a strong show of U.S. backing to firm up his hold on power.

One U.S. military team is here negotiating possible speeded arms delivery for Egypt and another is in Khartoum working with Sudanese military officials on what can be done to help what Haig called "this threat to the nation."

The U.S. measures seem to pay little heed to the argument of those who contend that the hostility of Sadat's Islamic extremist foes could be increased and broadened by a more visible American presence.

"In my view, the real thing the United States can do for Egypt and for stability in the region is to persuade Israel to moderate its policy on the West Bank," said Mohammed Sayed Yassin, a foreign policy expert at the Center for Strategic Studies in Cairo. He referred to Israeli expansion of settlements in the occupied territory.

However, Haig said today, "I think the process that is most important at the moment is to continue with the autonomy talks" on the future of the occupied territories, due to resume later this month.

A U.S. official traveling with Haig said he stressed to Israeli Prime Minister Menachem Begin when the two met here yesterday the U.S. view that progress would be more likely if Israel stopped expanding the settlements on the West Bank, but had gotten no commitment.

The agency that is jointly responsible with Begin's Cabinet for planning and funding the settlements, the World Zionist Organization, recently announced plans to increase the West Bank's Jewish population substantially in coming years.

Mubarak and Begin told Haig of their shared determination to go ahead with the autonomy talks and normalization of relations between Egypt and Israel, including Israel's return of the final third of the Sinai Peninsula next spring, the State Department official said.

"Prime Minister Begin was especially fervent in reaffirming his commitment to the turnover of the Sinai on schedule in April 1982," he added.

Israelis here with Begin said he is considering turning over slices of remaining Israeli-occupied Sinai territory before the April deadline as a gesture to reinforce Mubarak's determination to proceed with peacemaking.

Begin's foreign minister, Yitzhak Shamir, strongly opposed the idea, these sources said, and it will have to be thrashed out in the Israeli Cabinet in the coming weeks.

The U.S. official with Haig said the United States also is considering raising the level of its representation at the autonomy talks as a symbol of the increased need for progress. Washington currently is represented by ambassadors, a shift down from special presidential envoys Robert Strauss and Sol Linowitz of the Carter administration.

In a background briefing, the high State Department official went out of his way to suggest that the Reagan administration inherited the autonomy talks at a point when they were "totally stalled out." Now, as a result of "quiet diplomacy," they have resumed, he added.

Similarly, the official said Haig came into office facing a difficult dispute over composition of the international Sinai peacekeeping force due to control the Sinai after Israeli withdrawal in April, but smoothed over differences between Egypt and Israel and formed a course acceptable to both.

As Haig has since arriving here for Sadat's funeral, he emphasized U.S. faith in Mubarak's ability to assume Sadat's mantle as Egyptian leader and Middle East peacemaker. Without saying how, he also expressed belief that Mubarak simultaneously will be able to reduce the sharp discord dividing Egypt from Saudi Arabia since the peace treaty with Israel.

"I see a strong possibility because of the convergence of strategic outlooks and mutuality of interests between the two countries," he said.

Haig declined to say what weapons would be delivered to Egypt more swiftly following Sadat's assassination. The Egyptian government has been pressing for faster deliveries of M60 tanks, M113 armored personnel carriers, TOW antitank missiles and F16 warplanes.

Washington will not seek help from NATO allies to make available these weapons for delivery to Egypt, the U.S. official said, but may be forced to borrow from its own stockpiles.

The Reagan administration has before Congress a request to supply Sudan with $100 million in arms. Only l0 days ago, Mubarak -- then Sadat's vice president -- returned from Washington reportedly disappointed in the administration's response to an Egyptian request for more urgent action to help Sudan.

Clashes had been reported between Sudanese forces and Libyan troops in Chad along the southern Sudanese border. President Jaafar Nimeri, apparently facing increased opposition from within as well, suspended the Sudanese parliament a week ago and reshuffled his top leadership.

The Sudanese situation is part of what Haig has been calling "outside manipulation" or "Libyan mischief-making" in the area, U.S. officials said.