He had a key role managing relations with the United States and India whilst heading the nascent country's diplomatic service. As the senior-most diplomat of the Bangladesh movement in the United Nations delegation under Justice Abu Sayed Choudhury which was in New York in September 1971 to lobby for the Bangladesh cause at the General Assembly, he played a vital role in the delegation's lobbying efforts. He was also in communication with other governments, such as the Nixon administration in the United States and also with Senators, Congressmen, and high officials in the US Administration, World Bank, and IMF; he had the advantage as well of being familiar with decision-makers and the decision-making process having served as a diplomat in Washington 20 years earlier. Former colleague Syed Muazzem Ali described him as a "soft-spoken and scholarly diplomat" who was exceptional in articulating the cause and whose contributions were invaluable. He was one of the first high officials to reach Dhaka after its liberation, and was quartered with other senior officials in Bangabhaban until January 1972. He was also the highest Bangladeshi official in Dhaka until the acting president and cabinet arrived after independence; on his arrival in Dhaka he was driven under escort from the airport, becoming the first civilian official to lay a wreath at the ruins of the Shaheed Minar, an act planned to mark the first presence of the government in Dhaka. Already the effective head of the incipient foreign service, he became Foreign Secretary at the end of 1971, playing a key role in formulating Bangladesh's foreign policy. He then took up the position of Bangladesh's first Ambassador in Paris (1972–1976). The early part of this posting involved extensive travel in Africa to persuade African governments to recognise the independence of Bangladesh. In 1973 he represented Bangladesh at a Commonwealth conference for Youth Ministers in Lusaka. In 1975 he went to Morocco and, at a time of a shortage in supply of phosphates, managed to secure a substantial phosphate shipment for Bangladesh. In mid-1975 he was selected to be High Commissioner in the UK, which post he took up in early 1976. His two years in London (1976–1977) saw him Chairing the Commonwealth Conference on Human Ecology and Development and the Bangladesh government approved his recommendation that dual citizenship be permitted. Many people from Bangladesh were settled in the UK, whose remittances into Bangladesh were an important source of foreign exchange. He pointed out that to oblige them to forgo Bangladesh citizenship if they took up the benefits of British nationality was not conducive to the continued maintenance of their ties to the mother country.