The Reagan administration, seeking to avoid a clash with Congress over a proposed sale of 40 F15 jet fighters and other weapons to Saudi Arabia, has halted arms sales to all Middle Eastern countries for four to six weeks while it makes a "comprehensive review" of the defense needs of Israel and moderate Arab states.

The decision to put the sales on hold was revealed Wednesday by Richard W. Murphy, assistant secretary of state for Mideast affairs, in testimony before Congress. Administration sources said the hold is likely to last until April or May.

White House spokesman Larry Speakes added yesterday that the aim is to allow time to provide Congress with a "justification and rationale" for the sales that the administration eventually decides to make.

The move was a setback for officials, mainly in the Pentagon and the Mideast affairs bureau of the State Department, who wanted to use Saudi King Fahd's Feb. 11 visit here to wrap up agreement on the Saudi arms package and announce it quickly.

Administration sources acknowledged yesterday that they were deterred by strong indications that Congress does not want to face such a controversial issue so early in its new term. The sources said prominent Senate Republicans have been especially vocal in warning the administration to go slower and consult extensively with Congress.

A spokesman for Sen. Alan Cranston (D-Calif.) said that as of late yesterday 35 Democratic and 16 Republican senators had signed a letter to President Reagan opposing the Saudi sale at this time.

Sen. Richard G. Lugar (R-Ind.), chairman of the Foreign Relations Committee, welcomed the administration's decision and added, "I think it is unwise to make any sales currently until we see how it fits in" U.S. policy.

Speakes denied any connection between the Fahd visit and the halt in arms sales. "We have not suspended arms sales," he said. "We are just not sending anything up to Congress for the next four to six weeks."

But State Department officials said privately that the effect would be to delay for three to four months the possibility of a confrontation with Israel's congressional supporters over the Saudi sale. It also would buy more time to solve disputes within the administration about other potentially controversial sales to Jordan, Kuwait, Oman and Bahrain.

These officials said the administration's new timetable includes four to six weeks for the study and roughly two more months to weigh its conclusions and decide on proposals for Congress.

The officials also stressed that despite the delay, sentiment within the administration remains strongly in favor of the arms requests by Saudi Arabia and other moderate Arab governments. That was reiterated yesterday by Secretary of State George P. Shultz, who told the Foreign Relations Committee, "Our interests are arguably served by the strength of countries in addition to Israel."

Shultz argued that Saudi Arabia's use of U.S.-supplied jet fighters to shoot down an Iranian fighter last year had helped contain the Persian Gulf war between Iran and Iraq because it demonstrated that the Saudis are able to deter Iranian aggression.

"There's not much doubt in my mind that there will be additional sales," Shultz said, although he did not specify how far the administration might be willing to go in meeting the Saudi requests.