Chinese Communist Party leader Hu Yaobang said today that obstacles remain in ongoing talks with the Soviet Union, but there is no reason why China should not "have relations of friendship and good neighborliness with a socialist country that shares with us the longest common border."

Hu's remarks, made in a meeting with journalists from Hong Kong and Macao and reported in the official Chinese media, came as Chinese and Soviet negotiators in Moscow started a sixth round of talks on improving relations between them.

Chinese statements in recent weeks have led to speculation about a possible softening in Peking's preconditions for better Sino-Soviet relations, and anticipation of some movement in the talks. Although Hu, the general secretary of the party, provided some positive commentary, a notable part of his responses to the journalists' questions seemed designed to inject a note of caution into the discussion of improved relations.

The remarks by Hu and some other officials apparently have been aimed at reassuring western nations that China is not realigning its relations with the United States and the Soviet Union. The Chinese also seem to be conveying the message that the next move on relations is up to the Soviets.

Although Hu did not spell out what the obstacles were, the Chinese until recently have consistently specified them as the large Soviet troop presence on the Chinese border, the Soviet invasion of Afghanistan and Soviet support for the Vietnamese occupation of Cambodia.

The Chinese press and China's public statements had seemed to deemphasize the three obstacles following the marked improvement in tone of Sino-Soviet relations with the accession to power last month of the new Soviet leader, Mikhail Gorbachev. Hu and Gorbachev exchanged greetings, marking the first such exchange between the two Communist parties in more than two decades.

But at the end of March, Hu provided a more somber assessment of the prospects for an improvement in Sino-Soviet relations in an interview with the Peking correspondent of L'Unita, the Italian Communist Party daily.

The correspondent described Hu's attitude as one of "cautious realism." He said that Hu felt it was still not clear what the Soviets were thinking.

According to the Italian correspondent, "Hu said their method [the Soviet method] of approach was marked by a stagnation not easy to modify in a short time. The experience of the [past] couple of decades did not lead one to predict a swift improvement in relations between the two countries and their two parties . . . . It cannot be said there was no hope, but the hopes were still very vague."

But at the same time, the Chinese reluctance to specify what the obstacles are in their public statements has led to some speculation that some behind-the-scenes movement in Sino-Soviet relations might be under way.

At a regular press briefing on April 3, for example, a Chinese Foreign Ministry press spokesman was asked whether China was still insisting on the removal of the three obstacles. The spokesman replied that "there are obstacles in the relations between China and the Soviet Union, and this is a fact. We have stated on many occasions that it is hoped the Soviet Union will make some move."

But in response to another question, the spokesman declined to specify what the three obstacles were, saying simply that a western correspondent in Peking should know what they are.