Cambodian Premier Pol Pot charged yesterday that Vietnam launched "large-scale offensives" into his border areas during the past week, but that the invaders were repulsed.

In a lengthy and unusual interview broadcast by Phnom Penh Radio, the Cambodian leader accused Vietnam of "encreachment, provocation, aggression and invasion." He also accused Vietnam of subversion and coup attempts against his rule. At one point he charged that Hanoi cooperated with "CIA forces" in an attempt to topple him from power.

The Vietnamese radio denied the charges of invasion and called the Cambodian radio "a dirty instrument" for making the accusations.

In Washington, U.S. officials who have been following the growing confrontation said they have no evidence to confirm the Cambodian claims of major military engagements along the border in recent days. However, the officials said there is considerable evidence of Vietnamese preparations for military action in the near future.

American officials reported last week that 12 Vietnamese divisions had taken up positions along the border as tension between the two communist neighbors has risen sharply. Yesterday Pol Pot charged Vietnam with using "up to 11 divisions" in operations in the border areas during February and March.

The Cambodian leader's broadcast appeared to be his response to strong accusations and lengthy white papers published and broadcast by Hanoi last Friday. The Hanoi documents provided more detail than has been made public before about the nature and development of the quarrel between the two regimes.

The Hanoi documents, as monitored and translated by U.S. agencies, report that two countries were engaged in a post-liberation battle over off-shore islands when the U.S. merchant ship Mayaguez was seized by Cambodian forces on May 12, 1975. President Ford ordered a U.S. military assault that freed the crew at the cost of 18 Marines and 23 airmen killed.

Hanoi reported that Cambodian forces landed on Vietnam's Phuquoc Island on May 4, 1975, less than a week after the communist takeover of Saigon, and that Cambodian attackers also occupied Thochu island on May 10, 1975, and abducted 515 residents who have not been seen since.

Hanoi said its forces drove out the Cambodians late in May and temporarily occupied Wai Island, from which Cambodian attacks had been launched. The Mayaguez was seized 6 1/2 miles from Wai Island.

Officials here said yesterday that U.S. intelligence - which was in disarray in the immediate aftermath of the fall of Phnom Penh and Saigon - learned that Cambodia had ordered much more aggressive sea patrolling in the disputed area in an attempt to intercept Vietnamese craft. However, no warning was given by the United States to ships in the area until after the Mayaguez was seized.

The Vietnamese documents indicated that the main border dispute between the two countries pertains to seat rather than land boundaries. The question is import because there is believed to be oil beneath the continental shelf in the area in contention.

Pol Pot charged - and Vietnam last week denied - that Hanoi is seeking to weld all of Indochina into a "Federation" which Vietnam would dominate.

"By so doing, Vietnam would be able to control and dominate our party, state power, military, economy, and domestic and foreign policies; and also to turn Cambodia into a part of Vietnam and the Cambodian people into a minority nationality of Vietnam," Pol Pot said.

The Cambodian leader charged that beginning last Friday - the day on which Hanoi issued its documents - Vietnamese forces had invaded at least five areas. The first attack was at 6 a.m. Friday by a Vietnamese division near Kampot, he claimed.

In order to attain peace, Vietnam must "absolutely not interfere" in Cambodia's internal affairs and must respect its "independence, sovereignty and territorial integrity," Pol Pot declared.