Former World Bank president Robert S. McNamara, during a world conference of the Society for International Development today, urged creation of a world central bank to act as a lender of last resort and an insurer of banks that make risky loans to developing countries.

And in a panel discussion this morning, three experts in international finance considered the role of American banks in sustaining the less developed countries struggling to stay productive as recession undermines their creditworthiness.

McNamara told the 1,600 delegates that such a central bank would support the world banking system and encourage loans to developing nations.

Because of staggering debts burdening some Third World and Eastern European countries, raising the threat of default in some Latin American, African and Eastern nations, private banks have been wary of lending more money.

Because of the worldwide economic downturn and the danger that a few defaults could ripple throughout the global financial community, McNamara said, a mechanism like a world central bank is needed.

McNamara, chairman of the Overseas Development Council in Washington, didn't spell out how such a bank might be organized, but in a telephone interview before his address, he said it could take the form of an expanded version of the International Monetary Fund or an entirely new organization.

Although he hadn't worked out details of the plan, McNamara said he wanted to bring the idea before the world financial community