WASHINGTON, May 19.--The United States and Britain are reported to have agreed to head an international effort to shore up the precarious financial position of Pakistan.

The United States decision was reported to have been made last month in discussions between Henry A. Kissinger, White House assistant for national security affairs, Secretary of the Treasury John B. Connally and Robert S. McNamara, president of the World Bank.

Mr. McNamara is understood to have won a British pledge of cooperation during discussions in London April 22 and 23 with Prime Minister Heath and the Foreign Secretary, Sir Alec Douglas-Hume.

As a result, the World Bank and the international Monetary Fund will send survey teams to Pakistan next month as the first step in a four-stage program aimed at restoring vitally needed international economic assistance.

ASSURANCES SOUGHT

The foreign aid, however, will be contingent on moves by Pakistan s central Government to seek a political accommodation with the Bengalis in East Pakistan and to permit an international relief effort to assist destitute civilians there.

Muzaffar M. Ahmad, senior economic adviser to the Pakistani Government, is understood to have given assurances that Pakistan would comply in talks here during the last ten days with President Nixon, Mr. Kissinger, Secretary of State William P. Rogers and Joseph J. Sisco, Assistant Secretary of State for Near Eastern and South Asian Affairs..

Qualified informants in the State Department said that delegates of the 11-nation Aid to Pakistan Consortium would meet in Paris in mid-June to study a standby loan to Pakistan reported to range between $85 and $125- million.

Mr. Ahmad is known to have suggested during his discussions here that Pakistan urgently needs a standby loan of $100-million before July 1 and another of $500- million to 51-billion during the fiscal year ending June 30, 1972,

REPATRIATION SOUGHT

On March 25 Pakistani troops were ordered to suppress a movement for political autonomy backed by the predominantly Bengali population of East Pakistan. Since then Sheik Mujibur Rahman, head of the Awami League and leader of the autonomy movement, has reportedly been arrested, the economy of East Pakistan has been disrupted and an estimated 3 million refugees have crossed into neighboring India.

The State Department said today that it had impressed on Pakistani officials here the need for early voluntary repatriation of these refugees to East Pakistan. It also said that it was supporting the appeal issued today by Secretary General Thant for international aid to the refugees.

Charles W. Bray, 3d, the State Department spokesman, said that the United States had transferred $500,000 to the office of the United Nations High Commissioner for Refugees, Prince Sadruddin Aga Khan of Iran, to help feed the refugees in India. This sum, he said, had been taken from $5-million previously earmarked for refugee relief by United States voluntary agencies already working in India.

Pakistan has now indicated to the United Nations and to United States officials that she intends to admit United Nations and other international relief experts next month. The United States had warned Pakistan that its protracted resistance to doing so had harmed her international reputation and delayed the resumption of foreign aid.

All aid to Pakistan by the Aid to Pakistan Consortium-- including United States loans, food and military equipment--has been suspended since March 25. In the last 17 years, Pakistan has received more than $4- billion in United States aid.

FOUR-STAGE PROGRAM

After the talks with Mr. Ahmad, State Department officials made it clear that the United States would not resume economic or military aid to Pakistan until completion of the program.

The first stage, they said, would involve the surveys to he made by teams from the World Bank and the international Monetary Fund next month.

Secondly, they went on, Pakistan would be expected to prepare a "realistic" development plan covering both West and East Pakistan.

In the third stage, the officials said, the consortium which furnishes Pakistan with approximately $450-million annually, would review the reports by the World Bank, the international Monetary Fund and Pakistan. The consortium comprises the United States, Japan, Britain and other industrialized countries. The annual share or the United States is approximately $200- million.

Finally, State Department officials said, the consortium members would decide how much each would contribute.