Mexico found itself in financial limbo this morning after yesterday's nationalization of private banks and the unprecedented imposition of strict exchange controls.

Mexico's central bank governor resigned, apparently to protest the measures. Details on Page D10

Some political analysts saw the measures primarily as a move to placate the country's leftists and its peasant and labor leaders, and as an effort by outgoing President Jose Lopez Portillo to salvage, before leaving office Dec. 1, prestige tarnished badly by the present economic crisis with its overwhelming debts and precipitous devaluations.

"You have to hand it to him; it was quite a performance," said a Latin diplomat who asked to remain anonymous. "Here was a totally discredited man, and he knew it, and he got up there and turned himself into a hero to certain sectors of his party. Of course, the international banking community's confidence in him has to be zero at the moment. I don't envy his successor. He may have taken a bad situation and made it much worse."

Business leaders have reacted angrily to the new measures, with some terming them both "infantile" and "paternalistic."

Bank employes stood aimlessly outside the offices, which were ordered closed until Monday when they will reopen under state ownership. Extra policemen were stationed near the main doors of branches of most banks.

The key question of the moment is what the exchange rate will be when the banks reopen Monday.

Yesterday evening, when the airport black market was in full swing, it shot up to as high as 200 pesos to the dollar from roughly 100 in preceding days. But tourists arriving today hoping to take advantage of last month's major devaluation found there was almost nowhere to change their money.

Many businessmen here believe the peso may be set as low as 70 to the dollar under the new financial regime, at least for the short run, to try to draw back into Mexico some of the billions of dollars that Mexicans have deposited outside the country.

A spokesman for the Treasury Ministry, meanwhile, said this afternoon that "absolutely nothing is known, not even approximately" about the rate that will be fixed for most transactions.