NEW DELHI, July 5—Bengali insurgents have knocked out the electrical power station in Dacca, the East Pakistani capital, authoritative foreign sources reported here today. These sources, who received the information from contacts in Dacca, said the city had been blacked out since Saturday night.

Several foreign newsmen are in East Pakistan, but no news of the attack has come out of Dacca. The sources here speculated that reports were being blocked by the authorities or that the cable office had been shut by the power failure.

Another major East Pakistani town, Comilla, has been without power for over a week, its power plant reportedly also knocked out by insurgents. Comilla, a key rail and road junction about 50 miles south east of Dacca and close to the Indian border, has been a focus of increasing guerrilla activity against the Pakistani Army.

Since March 25, when the army began an offensive against the Bengali secession movement, It has been trying to subdue the Bengali population of 75 million. The army now controls most of the province, but there is resistance, particularly near the border with India, and this resistance appears to be widening and growing more effective.

Most Dramatic Move

The crippling of the Dacca power plant is the most dramatic act ascribed to the insurgents since the army seized control of the city in late March after killing several thousand civilians.

Few details are known of the attack, which came sometime Saturday night. The foreign sources here said the power plant's main transformed had been either destroyed or badly damaged.

Although the loss of electricity will cause considerable disruption in Dacca, it will not bring the havoc that would be caused in a Western capital. There are few tall buildings and therefore few elevators.

The airport—used mostly for bringing troops in from West Pakistan, which is 1,000 miles away across India—has an auxiliary power supply. This is also presumably true of the major hospitals, including the military hospital, which has been handling army casualties from all parts of East Pakistan.

Workers Have Gone

Factories in the Dacca area will be the hardest hit, but since the upheaval in March, the factories have been operating at a fraction of capacity because most of the workers have fled either to the country side or to India.

The foreign sources here did not know how wide an area had been affected by the black out or whether the army had taken reprisals against civilians.

The insurgents, known as the Mukti Fouj or Liberation Army, had vowed to step up activity as their response to President Agha Mohammad Yahya Khan's speech to the nation last Mon day night.

The speech, heralded by the Government as a plan for returning Pakistan to civilian rule, instead said that martial law would continue even after a civilian government was established. President Yahya, a general who is the martial‐law ruler of Pakistan, also said that a committee of experts‐named by him—not the National Assembly as originally promised— would draft a new constitution, He said that the Awami League, the East Pakistani party that won a national majority in last December's election, was still, and forever, banned.

In New Delhi today, India charged that Pakistani troops in East Pakistan had been shelling Indian border villages and intruding into Indian territory almost daily.

The Foreign Ministry said that the Pakistani Army since March 25 bad committed 102 serious border violations—killing 65 Indians, wounding 112 and kidnapping 23.

The Indian charge followed Pakistan's assertion yesterday that Indian planes had bombed some East Pakistani villages. India dismissed the accusation as baseless.