Australia confirmed today that it would assist the United States in monitoring splashdown tests of the new MX missile in international water in the Tasman Sea.

A newspaper report on the tests appeared yesterday morning, and Defense Minister Kim Beazley later confirmed that refueling and food facilities would be provided in Sydney for U.S. planes monitoring them. The news sparked an immediate protest from the left wing of the Labor Party and the Australian Democrats.

Five left-wing members of Parliament from New South Wales sent a message to Prime Minister Robert Hawke seeking to have the policy overturned. The leader of the Democrats, Senator Don Chipp, said the government had become "the puppet of the Reagan administration."

Beazley said the original commitment had been made by the previous conservative government of Malcolm Fraser, and that the Labor government would be in breach of the agreement if it reneged.

"It is taken in the light of a commitment to the U.S.-Australian alliance which does not change with this government," Beazley said. He said the missiles would not carry nuclear devices or material, and that the government's involvement did not conflict with its support for a nuclear free zone in the South Pacific or its United Nations support for a nuclear freeze.

The United States has been using the Marshall Islands as a splashdown site for MX missiles fired from the U.S. West Coast, but defense officials are anxious to test the missile's accuracy over its estimated maximum range of 7,800 miles. It was first planned for the missiles to land close to Tasmania, but the Labor government insisted that the splashdown should be farther out in international waters.

Senator Bruce Childs, from Labor's left wing, said the party had placed the highest priority on nuclear arms limitation. "The fact that there will not be a nuclear warhead does not get away from the spirit of that policy."