WASHINGTON, April 13.-The State Department conceded today that the United States had been selling approximately $2.5-million worth of ammunition yearly to Pakistan since 1967 as "nonlethal" equipment.

Until now, the Administration has insisted that only minimal amounts of "nonlethal" military supplies have been furnished to Pakistan. it has described such supplies as military personnel carriers and communications equipment.

Robert J. McCloskey, the State Department spokesman, disclosed in response to questions that sales of military items to Pakistan- both on commercial and on credit terms- had in fact been running at "just under" $10 million a year.

About 25 per cent of this-or about $2.5 million-has been in the form of ammunition, he said.

Mr. McCloskey explained that United States supplies of both lethal and nonlethal equipment had been embargoed when the India-Pakistani fighting erupted in 1965.

"In 1966 and 1967 the embargo was lifted to permit sales of what we have described as nonlethal equipment," Mr. McCloskey said, "although I acknowledge that to some extent it included ammunition."

PROTESTS IN U.S.

Since March 25 when the Pakistani Government used troops to suppress a movement for political autonomy sponsored by the Awami League, the predominantly Bengali political party of East Pakistan, there have been protests in the United States Congress, the press and among the public that the Pakistani forces were using United States supplied arms.

Despite Pakistani's expulsion of American and other foreign newsmen and her tight censorship, there have been widespread reports of killing and damage in East Pakistan.

Mr. McCloskey said that the State Department was unable to ascertain when the last United States arms deliveries were made to Pakistan, what was now en route or what was being prepared for shipment.

Defense Department sources said that intensive efforts began last weekend to assemble from Army, Navy, Air Force and commercial records a composite picture of what the United States military items had been sold to Pakistan in the last four years. However, they warned, it will require "more computer runs" and possibly two more days before the full facts are known.

At the same time Mr. McCloskey was able to furnish figures from the Agency for international Development showing that there were 700,000 tons of American wheat- or a four months' supply-now available in East Pakistan for civilian needs.

There are an additional 200,000 tons aboard ships awaiting unloading in East Pakistani ports, he said, and 300,000 tons more have been authorized for shipment as soon as delivery bottlenecks can be eliminated.

Mr. McCloskey said that the United States had stressed to the Pakistani Government that the current problem was not one of supply but of distribution. Ports, roads and railways have been disrupted, he said, and port labor in East Pakistan is unavailable-presumably because of widespread fighting.

Mr. McCloskey acknowledged that President Agha Mohammad Yahya Khan had still not responded to proposals by the United Nations and the United States for an international relief effort in East Pakistan. He reiterated the willingness of the United States to assist in such an effort.

Meanwhile, the State Department disclosed that the United States was selling to Ceylon-via Britain-six Bell OH-133-H, or "bubble" type, helicopters to help suppress the left-wing guerrilla uprising in that country.

In 1949, it was said, Ceylon bought-on military-credit terms-three Bell helicopters, each valued at 8125,000 new. The actual sales price was not disclosed although the State Department said that spare parts for the craft were flown to Colombo, yesterday in an Air Force jet transport.

The six smaller Bell craft-a type widely used in this country for police surveillance- are being sold at "nominal" costs, sources said. They pointed out that Ceylon had asked for helicopters from both the United States and Britain although Britain had none available.

Because Britain was the traditional arms supplier to Commonwealth countries, they said, the sale of the helicopters was a sensible triangular arrangement."