The Reagan administration yesterday unveiled the first of its controversial Middle East arms sales requests by asking Congress to approve up to $1.9 billion in weapons for Jordan, including new antiaircraft missiles.

At the same time, King Hussein of Jordan made a speech at the United Nations apparently aimed in part at satisfying congressional conditions before approving any arms sale to Jordan. "We are prepared to negotiate, under appropriate auspices, with the government of Israel, promptly and directly, under the basic tenets of Security Council Resolutions 242 and 338," the king said.

The two resolutions are regarded by the United States as the basis for any new negotiations and have become a U.S. acid test of Arab willingness to recognize and negotiate with Israel. They call upon Israel to withdraw from Arab territories occupied in the 1967 Arab-Israeli war in return for Arab peace with Israel.

The administration has tried for months to get the king to affirm publicly his recognition of Israel and willingness to enter direct talks with the Jewish state. His statement at the U.N. was the closest he has come to those positions.

Hussein still insisted, however, that the "appropriate auspices" should be an international conference hosted by the U.N. with Soviet participation, a proposal rejected by the United States and Israel, Washington Post correspondent John M. Goshko reported from the U.N.

The administration's Jordanian arms request, which likely will be followed by several others for Saudi Arabia, seems certain to trigger a new confrontation between Congress and the administration over Middle East policy, particularly administration plans to sell billions of dollars in weapons to Jordan and Saudi Arabia despite stiff opposition from Israel and its supporters here.

Congress adopted an amendment last June to the $250 million supplemental aid appropriation for Jordan barring the sale of new advanced American weapons unless King Hussein committed himself publicly to recognize Israel and to negotiate "promptly and directly" with the Jewish state.

Sen. Richard G. Lugar (R-Ind.), chairman of the Senate Foreign Relations Committee, issued a statement yesterday saying the king's steps to date still fell short of meeting congressional strictures and that further steps would be needed to gain Congress' support for the sale.

Meanwhile, pro-Israeli groups here insisted that the king had offered nothing new in his U.N. speech. The American Israel Political Affairs Committee issued a statement saying the king had still failed to end the state of belligerency between Jordan and Israel or take "an irrevocable step toward peace."

The administration had been expected to submit its arms sales package for Saudi Arabia first. But the kingdom is now reported to be having second thoughts about the details of its own initial requests for various kinds of missiles following its decision to purchase from Britain 72 European-made Tornado jets instead of more F15s from the United States.

In addition, King Hussein is scheduled to meet President Reagan at the White House Monday, and a senior administration official said yesterday he wanted to send an "unambiguous signal" of U.S. support for the king's recent peace initiatives.

Earlier, the president issued a statement strongly defending the arms sale to Jordan as "essential" to conveying "a powerful message" of U.S. political support and to provide Jordan with adequate air defense against attack "by the adversaries of peace."

"I remain totally committed to helping Israel to ensure its security, survival and well-being and to maintaining its decisive advantage over any combination of potential adversaries," he said. "The arms transfer which I am proposing for Jordan does not jeopardize this policy."

The senior official described the arms package as containing "a limited quantity of defensive arms" for Jordan. He presented a 14-page document stressing Jordan's need to defend itself primarily against threats from Syria.

The package includes 40 F20 or F16 advanced fighters; 12 mobile Improved Hawk surface-to-air missile batteries and equipment to convert its 14 batteries into mobile units; 72 Stinger shoulder-fired surface-to-air missiles and 36 reloads; 300 AIM-9P4 infrared air-to-air missiles and 32 Bradley Fighting Vehicles.

The cost of the package, the senior official said, would be either $1.55 billion or $1.9 billion depending on whether Jordan bought the F20 or the air defense variant of the F16. This would not be known until the Air Force decided which of the two it plans to buy itself, he said. The F16, made by General Dynamics Corp., would cost more than the Northrop Corp. F20.

The senior official said it was not clear how the arms package would be financed, or how much the administration would ask Congress to provide. He indicated that funding would come from a combination of sources, including Jordan, the United States and "other Arab countries," presumably Saudi Arabia.

The administration yesterday provided Congress with only informal notification of the arms sale. Both houses of Congress are expected to hold hearings on the sale and opponents now believe they have to votes to defeat the proposal.