The Soviet Union, using diplomatic techniques that caused an uproar here, has sharply criticized the government's plan to allow basing of U.S. B52s in Australia and said this could make the country "a nuclear target."

Soviet Ambassador Nikolai Soudarikov invited hal a dozen senior Australian political reporters to lunch this week and delivered a tirade against Conservative Prime Minister Malcolm Fraser's anti-Soviet policies.

Even by the freewheeling standards of diplomacy in Australia's bush capital -- Canberra is built on an old sheep ranch and open-shirt barbecues are the preferred entertainment -- it was an unusual performance.

Fraser, who imposed a freeze on Australian relations with the Soviet Union after its invasion of Afghanistan, reacted by telling the Parliament today that Australia would change its attitutde toward Moscow "only if the Soviet Union changes its policies."

He attack Soudarikov's comments to journalists as "an improper way of conducting relations between our countries. Accusations to journalists, however eminent, represent an improper way of conducting relationships between countries."

Fraser's reaction was an indication of the sensitivity of what the Soviet ambassador had said. He is one of the most experienced Soviet diplomats to serve in Ganberra, with posts in China, Vietnam and North Korea before coming here 15 months ago.

The Fraser government wants the United States to use Australian Air Force bases for its B52 bombers, has invited the United States to base warships at Cockburn Sound on the western coast near Perth and has approved expansion of a huge U.S. intelligence facility on the outskirts of Alice Springs in the center of the country.

It was these initiatives that Soudarikov singled out as being the reason Australia "could become a nuclear target." He would not expand on his comment but repeated it when questioned by the Australian journalists sharing his table.

Soudarikov presented a long list of criticisms of Australian policy while insisting that Moscow wanted "friendly relations" with Australia. He complained that Australia had imposed tougher sanctions since the invasion of Afghanistan than any other country including the United States.

One example he cited was that new embassies were being built in Moscow and Washington despite Afghanistan while the Australian government refused to let the Soviets build a new embassy complex in the Australian capital.

"We are working from a second-rate motel place on Canberra Avenue [one of the few tacky streets in the carefully planned capital] and your government won't let us have an empty piece of land near the Indonesian Embassy, and won't tell us why," he complained.

Questioned, he said it "did not matter" that the prime block he prized was directly opposite the U.S. Embassy, the major reason the Australian government has been diverting the Soviets from it for years.

Diplomats here professed amazement that the ambassador criticized Australia's government by talking to journalists. Some said Soudarikov might have miscalculated by thinking the journalists would simply report his theme that the Soviet Union was ready to "thaw" the relationship between Moscow and Canberra.

Fraser, throughout his 25 years in politics and especially as prime minister since 1975, has been strongly critical of the Soviet Union. He has ruged the United States to use Australian facilities for military purposes and has argued for conservative "proprieties" -- which emphatically do not include Soviet diplomats using the Australian press as a conduit for attacks on his policies.

At the lunch, Soudarikov said there should be more trade, cultural and social links between the two countries. He also said Australia had to make the first move by indicating its interest in improving relations. "We will not beg Australia to have better relations," Soudarikov said.

Fraser's answer today was, "If the ambassador really wishes to advance relationships between his country and mine, the way to do is clear." He left no doubt that Australia would neither discourage U.S. military and intelligence activities in Australia nor back away from criticism of the Soviet presence in Afghanistan as a precondition.