The U.S. government will play an important role in implementing the Zimbabwe-Rhodesian cease-fire informally agreed upon in London, U.S. officials said yesterday, providing planes to airlift the British Commonwealth troops that will police the truce.

In another development, the Senate voted 90-0 yesterday for a resolution calling on President Carter to lift current U.S. economic sanctions against Zimbabwe-Rhodesia as soon as the British resumed control of the breakaway colony, or by Jan. 31 at the latest.

State Department officials confirmed that the United States would make up for Britain's shortage of long-range air transport needed to put some 600 troops into Zimbabwe-Rhodesia.

Both Prime Minister Abel Muzorewa and the Patriotic Front guerrillas who oppose him have agreed to a cease-fire negotiated by the British, although the date it will take effect and other details remain to be fixed.

A spokesman for the Defense Department said the Military Airlift Command will provide two giant C5 jet air transports and 10 smaller C141s, starting next week for a two-week airlift from a Royal Air Force base in Britain to Salisbury.

U.S. sources said the British government, anticipating the agreement virtually concluded Wednesday in London, had requested two weeks ago that the airlift be provided, with Britain covering the costs.

Sen. Jesse Helms (R-N.C), a principal supporter of Prime Minister Muzorewa's Salisbury government, asserted yesterday that the Senate's latest action on sanctions is moot since "by Christmas the sanctions will be lifted" in any event.

Helms said that when he met privately with Secretary of State Cyrus Vance Monday, he received assurances that the administration now will have "no choice but to lift the sanctions" imposed in concert with U.S. resolutions.

Helms said that he saw in the U.S. provision of airlift aid a sign of good faith on the part of the administration.

In the ongoing London talks, the Patriotic Front guerrillas fighting Muzorewa withheld their complete approval on the basis that the final disposition of troops had not been determined.

President Kenneth Kaunda of Zambia issued a statement in Lusaka welcoming the breakthrough in the London talks. In Salisbury, the military command announced that on the day of the tentative settlement, the civil war cost the lives of 32 persons.