A Chinese leader said today for the first time since fighting began a week ago that Peking does not intend to attack Vietnam's populous Red River Delta or its capital at Hanoi, although the Vietnamese said Chinese attacks continued as deep as 25 miles inside their territory.

Vice Premier Wang Chen declined to say, however, when the nine-day-old Chinese invasion would end. "we are still in the process of teaching Vietnam a good lesson," he said, responding to journalists' questions before a Peking banquet for British Industry Minister Eric Varley.

Chinese leaders repeatedly have said their move into Vietnam is "limited in scope and duration," a phrase that Wang used again. Until today, however, Peking had not specifically ruled out an attack on Hanoi, about 100 to 150 miles from the uneven border.

Wang's statement appeared to support the view of many foreign analysts that Chinese attacks on key rail and road lines leading to Hanoi are designed to frighten and weaken Hanoi's army and government, but not to gain access to the capital.

Peking has said what it calls its "counterattack" against Vietnam is designed to punish Hanoi for raids into Chinese border communities and discourage further military adventures like Vietnam's invasion of Cambodia.

Reaffirming this justification, Chinese Finance Minister Chang Ching-fu pledged at a Peking banquet for visiting Treasury Secretary W. Michael Blumenthal that once Peking considers Hanoi appropriately chastised, "Chinese frontier troops will strictly keep to defending the border of their own country."

The official Vietnam News Agency said tonight that clashes continued near the key border towns of Laocai, Langson and Caobang, reported centers of the fighting for the past few days. Vietnam said it "wiped out" 4,000 more Chinese soldiers Thursday and Friday, bringing the reported total of Chinese killed or wounded in the first week of the border war to 16,000.

Foreign analysts consider the casualty figure exaggerated. The Vietnamese did not mention their own casualties and the Chinese have yet to report publicly on total casualties

A Chinese document disclosed by Peking correspondents reported 10,000 Vietnamese and 2,000 to 3,000 Chinese casualties in the first two days of fighting, but this also was considered inflated by foreign analysts.

Hanoi Radio has focused lately on fighting in the area of the northwest border town of Laocai, captured by the Chinese but with large Vietnamese forces to the southwest.Vietnam has said the Chinese have launched new tank and artillery attacks in the area.

American journalists who visited the area early Friday said the Chinese artillery barrages were more intense than any they had heard during the U.S. involvement in the war in South Vietnam.

Analysts in Bankgkok said that in addition to the Chinese attacks on towns commanding the main roads to Hanoi and along the border, there appeared to be some Chinese activity near the far northwestern Vietnamese town of Laichau. Some Chinese troops may be moving south of that city along Highway Six, one analyst suggested.

Chinese troops are said to threaten or control all principal Vietnamese towns and cities in the border area. Some Chinese troops in the Caobang area are believed to have penetrated at least 20 miles inside Vietnam.

At the United Nations yesterday, Vietnamese delegate Ha Van Lau said 25 Chinese divisions with artillery and air support had penetrated his country at some places up to 25 miles from the border. He said the Chinese force was "higher than the number of U.S. ground troops when their aggression against Vietnam was at the peak."

A force of 25 divisions would number about 250,000 troops. This matches Western estimates of the Chinese force, although most of those troops are reported to be still on the Chinese side of the border. About 550,00 American military personnel were stationed in South Vietnam during the height of U.S. involvement there in the late 1960s. The large majority were support troops.

Analysts here and in Bangkok have suggested that at most points along the broad Chinese invasion front Peking's troops probably are no more than three to five miles inside Vietnam.

The Vietnam News Agency today issued a reception speech by Vietnamese Army Chief of Staff Van Tien Dung promising an eventual Chinese defeat. He thanked the Soviet Union and other countries for their support.

The Soviet military attache in Hanoi repeated the Soviet line that Hacan defend itself but that it has "reliable friends." Moscow has supported Hanoi with a recent airlift. Several Soviet ships and planes also seem to be operating off the Vietnamese and Chinese coasts to monitor Chinese military activity.

Peking maintained its virtual press blackout on its progress in the war. Instead, it published more short articles describing incidents of bravery by Chinese soldiers and good feeling between Vietnamese villagers and invading Chinese forces.

One correspondent of the New China News Agency, writing from the "border front," said a Chinese unit "destroyed enemy positions on a hilltop with artillery barrages and followed this up by wiping out the enemy."

Then the same unit sent soldiers down the hill to the house of an elderly Vietnamese woman to "fetch drinking water, cook the meal, clean the house and feed the animals. The old woman thanked the Chinese soldiers profusely and offered them bowls of rice soup."

Other women in the same village complained of Vietnamese troops breaking or stealing their property, the Chinese reporter said.

The Chinese agency also reported the exploits of Chen Cpuan-kang, a soldier who, it said, killed or wounded 10 Vietnamese troops when caught behind enemy lines. At one point the shot and wounded a Vietnamese soldier, killed another soldier trying to rescue the first man. and then "as the wounded man was crawling back he received another bullet and never got up," the agency reported.

The Vietnam News Agency said Hanoi's forces destroyed or damaged 100 Chinese military vehicles in fighting Thursday and Friday. It said 20 tanks and armored cars, eight cannons and heavy mortars were blasted and large quantities of weapons were seized.

Analysts continued to report some main force Vietnamese Army units moving toward the border area. The principal Vietnamese border forces are militia, whose members are parttime soldiers, and regional forces, made up of fulltime troops stationed in the border area.

The regional forces reportedly have the same uniforms and much of the same equipment as main force army units. But their troops are not thought to have as much combat experience. Main force Vietnamese units protecting Hanoi appear to have remained in place and as far as is known have not moved up to engage the Chinese.

Broadcasts by China and its Khmer Rouge guerrilla allies in Cambodia continued to report losses by Vietnamese troops trying to end resistance to Hanoi's new handpicked government in Phnom Penh. The Vietnam News Agency quoted an editorial in the Hanoi paper Nhan Dan rejecting any formula for Vietnamese troops leaving Cambodia, where Hanoi claims it has no troops, in return for a Chinese pullback from Vietnam.

Such a formula was a key element in an American cease-fire proposal at the U.N. Security Council, where the Indochina conflict is being debated.