NEW DELHI.-Prime Minister Indira Gandhi accused the world powers today of not doing enough about the civil war In East Pakistan and said India may have to intake all means as may be necessary to ensure our own security. "

As she spoke before Parliament, the Indian Army took over control of a border post in Assam after it was shelled by Pakistani troops, officials here said. The mortar shelling of the post of Sutarkandi, about eight miles from the town of Karimganj, had died away by this evening, the Press Trust of India news agency reported.

The agency said the post had been manned by the border security force, two of whom were killed in the firing. It also said three civilians died and 25 were wounded. Mrs. Gandhi said more than 3.5 million refugees have fled from East Pakistan into India and that the influx is continuing at the rate of 60,000 a day, threatening to disrupt the Indian economy and drain the government's resources.

"I have pleaded with all countries to recognize this threat to peace on the subcontinent," she declared. "If the world does not take heed we shall be constrained to take all means as may be necessary to ensure our own security and for the preservation of the structure of social and economic life. I say this with full sense of responsibility."

She did not elaborate, but she hinted strongly that a military solution was one possibility.

"Our nation, our people are dedicated to peace and are not given to talking In terms of war or threat of war," she said. "But I should like to caution our people that we may be called upon to bear still heavier burdens."

Mrs Gandhi spoke on the refugee situation after unruly scenes in the Lok Sabha (lower house) culminating in a walkout by most opposition members who wanted a full- scale debate in the East Pakistan situation and diplomatic recognition Of the independent republic of Bangla Desh (Bengali nation), the secessionist name for the east wing of Pakistan.

Defense Minister Jagjivan Ram said Pakistani troops had crossed the Indian border seven times since the trouble began in East Pakistan on March 25. There had been 43 incidents of firing across the border and 11 violations of air space.

Instructions had been given that intruding aircraft were to be shot down if they disobeyed orders to return to Pakistan territory, he said.

Deputy Foreign Minister Surendra Pal Singh told Parliament that since the Pakistan civil war 38 Indian citizens had been killed, 19 injured and 14 kidnapped in border violations by the Pakistan army.