Many major commercial banks yesterday balked at providing an additional $20 billion in new loans to developing nations without government assurances that will lessen the risks of any new loans to those countries, government and banking sources said.

But U.S. government officials and executives of multilateral institutions such as the International Monetary Fund and the World Bank said they wanted a commitment of new lending before considering any steps that might make it less risky for the banks, these sources said.

About 60 banks from around the world met with representatives of the U.S. Treasury, the World Bank, the IMF and the Inter-American Development Bank yesterday to discuss proposals to ease the world debt crisis that were put forth three weeks ago by U.S. Treasury Secretary James A. Baker III.

Baker urged that major multinational banks increase their lending to debtor nations -- most of them in Latin America -- by $20 billion over the next three years and that the multinational institutions boost lending by $9 billion. The Baker proposals also call on the debtor nations themselves to take steps to reform their economies: reducing the size of the often-inefficient state sector and putting more emphasis upon so-called market forces.

The Baker plan is a recognition by the U.S. government that Latin American debtor nations cannot tolerate many more years of the austerity measures they have been following in order to pay the interest on their debts -- which today total about $360 billion.

Yesterday's meeting was held under the auspices of the Institute of International Finance, a group of major banks that was formed in the aftermath of the Latin American debt crisis, which began in August 1982 when Mexico announced it had run out of money.

Sources at the meeting said that the banks themselves were divided on the Baker proposal, with officials such as Citibank Vice Chairman Hans Angermueller more supportive of the Baker plan than many other banks' representatives.

But many banks said they could not commit themselves to increasing their lending to Latin America because they already have too many loans to the region and cannot justify increasing their exposure unless governments are willing to share in the risk.

"It's no longer a banking problem," said one U.S. banker in attendance. "You're not talking about bailing out the banks, you're talking about bailing out the countries." Commercial banks have lent Latin American countries about $230 billion to $240 billion.

David Mulford, the assistant secretary of the Treasury for international affairs, told the bankers that it is in their best interest to increase their lending to the region so that the countries can resume economic growth.

One banker at the meeting said each side wanted the other to "show their cards first." Many banks wanted assurances that the industrial governments would guarantee increased bank loans, while the U.S. government officials and those from the multilateral institutions wanted bank commitments before they were willing to talk about any risk-reducing actions for the banks.

Initially, Baker wanted to include World Bank guarantees for some new private bank loans to developing countries, mainly in Latin America, but he had to kill that part of the proposal after it met with resistance from European finance ministers and executives of the World Bank itself. Baker made his proposal at the annual meeting of the IMF and the World Bank in Seoul.

One banker in attendance said that the meeting progressed about as far as could be expected under the circumstances. "There are a number of issues that have got to be ironed out, and they cannot be done in big sessions like today's," he said.