Secretary of State Cyrus R. Vance will travel to Moscow later this month for high-level strategic arms talks and discussions on the future of Africa, administration sources said yesterday.

Final plans for the Vance trip, including specific dates, have not been set, but authoritative sources said both countries had agreed in principle on the desirability of the visit.

The plan to send Vance to Moscow is one result of a decision by President Carter early last month to press ahead now to complete the stalled negotiations on a new Strategic Arms Limitation Talks (SALT) agreement, sources said.

But at the same time the administration was making this decision to press ahead on SALT, key officials at the White House began to speak of possible "linkage" between the fate of the SALT talks and Soviet involvement in the Horn of Africa. The Soviets have called this an extraneous issue.

Vance will raise U.S. concerns about Soviet intentions in Africa during his visit to Moscow, administration sources said.

One authoritative administration official told a small group of reporters yesterday the United States must reach a broad understanding with the Soviets "one way or the other" about their ultimate ambitions in Africa. Continued unrestrained superpower competition on that continent "can really gnaw away at the fabric of our relationship" with Soviets, this official said.

Amplifying on earlier statements by Zbigniew Brzezinski, President Carter's national security adviser, on the potential negative impact on the SALT talks of continued Soviet adventures in Africa, this official suggested the United States could not sustain the dentente relationship with Moscow without a clearer understanding of Soviet policy in Africa.

This source can only be identified as an administration official under the ground rules of his meeting with reporters. His position in the executive branch puts him at the center of policy discussions on national security matters.

A senior official in the State Department said yesterday that Vance also thinks the Soviets and the United States must agree on some "rules of the game" and "limits" for their competition in Africa, which this official predicted will continue.

This State Department official said Vance would not "pound on the table" in Moscow and demand a change in Soviet policy, but he would try to "reason" it through with them," to demonstrate the dangers of continued Soviet-Cuban adventures in Africa.

A repetition of Soviet and Cuban military involvement in Rhodesia or elsewhere in Southern Africa could have "much graver" consequences for Soviet-American relations than the current imvolvement in Ethiopia, this official said.

The administration official who spoke to reporters yesterday was asked what threat the United States could use to induce the Soviets to moderate their African policy. The official said he would prefer to save the "or else," as it was called, for direct meetings with the Soviets. He declined to be more specific.

Administration officials have been frustrated for weeks at their inability to dissuade the Soviets and Cubans from their involvement in Ethiopia.

Yesterday administration sources said a deputy Soviet defense minister is visiting Maputo, capital of Mozambique, where he is discussing possible arms supplies for one faction of Rhodesian guerrillas headed by Robert Mugabe. In the past, most assistance to this faction has come from China, and the officials suggested this could be an ominous sign of increased Soviet involvement in Rhodesia.

Vance's trip to Moscow will substitute for a meeting planned earlier with Soviet Foreign Minister Andrei A. Gromyko elsewhere in Europe. According to a State Department source, a Moscow meeting was favored by both countries as a way to put high-level political impetus into the stalled SALT process.

The last major progress on new SALT pacts was made in September, when Gromyko visited Washington.

U.S. officials believe the Soviet leadership has undertaken a thorough review of the relationship with the United States. Some officials speculate that this review will be held in abeyance pending the outcome of the Vance visit.

A recent authoritative commentary in the official Soviet newspaper Pravda said the U.S. government appeared to be wavering between policy options, and urged the Carter administration to demonstrate its commitment to SALT.