The United States has not halted shipment of all military weapons to Pakistan because this would turn the regime of President Yahya Khan to "other areas of supply," a senior State Department official said yesterday.

Deputy Assistant Secretary of State Christopher Van Pollen told a Senate subcommittee hearing on refugee problems in Pakistan and India that an outright embargo on arms shipments would be interpreted by Pakistan as "a sanction and intrusion into internal problems."

In response to sharp questioning by subcommittee chairman Sen. Edward M. Kennedy (D-Mass.), Van Hollen said such an embargo would undermine U.S. efforts to persuade the Pakistani government to establish favorable conditions for the return to East Pakistan of a reported six million refugees now in India.

Showing impatience with his witness, Kennedy shot back, "The reason for our supplying arms is that if we don't, China or Russia will and we want to keep our leverage. Well, where is our leverage now?"

Van Hollen said the "other areas" to which Yahya could turn included Western Europe and Communist China. China, he said, has never ceased supplying Pakistan with arms.

When fighting between East Pakistani dissidents and government forces broke out last March, Van Hollen said, the United States "began a close review" of its policies and "made certain adjustments and took certain steps."

This "interim action" included placing a "hold" on sales of military equipment under Defense Department control and a freeze on issuing new licenses to ship arms to Pakistan as well as renewing expired permits.

Kennedy termed government explanations to date "highly misleading" and said he was planning to submit legislation to halt all weapons shipments to Pakistan "at the earliest possible moment."

Van Pollen conceded that official statements had caused "some confusion," but he denied that there was any attempt to "mislead" the public.

[In a report from New Delhi, Reuter quoted Indian Foreign Minister Swaran Singh as saying U.S. government spokesmen were contradicting themselves over the sale of arms to Pakistan. "The more I have looked into it deeply, the greater is the concern," he said.]

Another government witness, John W. Sipes, director of the Office of Munitions Control, denied recent news reports that two Pakistan flag carriers were sailing from the United States to Pakistan with military weapons including four planes. The only munitions aboard either ship were 2000 rounds of "sporting type" .22 cal. ammunition, he said.

As to whether there were any rifles aboard, Sipes said, "if there are, they're sporting type too, for use in safaris."

"Safaris in East Pakistan," Kennedy retorted, to laughter from about 70 persons attending the session. At a separate briefing, State Department spokesman Charles Bray denied reports that agreement was reached by an 11-nation consortium in Paris last week to halt all aid to Pakistan,

"Formal aid commitments to Pakistan were neither invoked nor considered and, contrary to press reports, no agreement was reached to postpone indefinitely new economic development assistance to Pakistan," Bray said.