The United States and its NATO allies have begun discussing a gradual dismantling of sanctions against the military regime in Poland, according to administration sources.

No decisions are expected before the NATO ministerial meeting in Paris June 9-10, and even then the position of the alliance is likely to hinge on the outcome of the trip of Pope John Paul II to his native land scheduled to begin June 16.

However, preliminary talks already have been held here and in Europe on ways of easing the trade and other restrictions adopted in response to the imposition of martial law in Poland in December, 1981. The sanctions include bans on further extensions of official credit and credit insurance, denial of trade benefits, curtailment of Polish civil aviation and fishing rights and limits on cultural exchanges.

Last Tuesday President Reagan lifted an additional sanction he had imposed on the Soviet Union for its part in the Polish military takeover, announcing that Washington and Moscow will begin talks soon on a new long-term grain agreement. Such negotiations had been suspended following the martial law order in Poland.

Administration officials insisted last week that this turnaround was not intended as a political signal, and they have said nothing publicly about lifting sanctions against Poland.

But informed sources said that in confidential discussions in Europe, Assistant Secretary of State Richard Burt suggested that the United States and the allies explore ways to lift the sanctions gradually, with each step conditioned on reciprocal actions by the Polish regime.

Burt's suggestion and other ideas about policy toward Poland are said to have been under consideration in Brussels in the past two weeks in the North Atlantic Council, composed of representatives of all the NATO countries.

In Paris, meanwhile, representatives of the State and Treasury departments participated in informal talks last week with representatives of other creditor nations on ways to handle Poland's official debts to the West, estimated at $13.7 billion. Most of the western nations have followed the U.S. lead in refusing official debt rescheduling talks with the Warsaw government since martial law was decreed.

Despite this behind-the-scenes activity, a senior administration official said President Reagan has made no decision to lift or even to amend the sanctions he imposed on Poland in reaction to the suppression of the Solidarity trade union under the rule of Gen. Wojciech Jaruzelski.

Reagan was depicted by this source as resistant to anything that would reduce the external pressure on Poland so long as the repression continues.

In the White House view the situation in Poland is ambiguous at best, with positive internal measures and gestures alternating with negative ones. "We have no intention of giving the Poles any goodies when the situation is as ambiguous as it has been in this period," a White House official said.

Following a White House briefing for congressional leaders on the long-term Soviet grain agreement, some prominent lawmakers sounded a different note, however. Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) said, "I think it is clear to everyone now that Poland is better off now than they were two years ago or even a year ago, and I think this was an appropriate time to renew efforts to renew dependable trade with the Soviet Union."

Even the most determined and influential White House opponents of an early shift on Poland are aware of growing sentiment for a change among some European allies. Poland reportedly has come up in earlier discussions between Reagan and West German Chancellor Helmut Kohl, who has been urging greater allied flexibility. State Department officials listed Poland among the items likely to be discussed by the leaders at the seven-nation summit at Williamsburg, Va., later this week.

Internal administration discussion of policy changes toward Poland were spurred by the official lifting of martial law last December, on the anniversary of the 1981 crackdown. However, strict controls through other means made this action seem more cosmetic than substantive.

An interagency study under the leadership of the State Department, completed earlier this year, was said by a knowledgeable source to advocate authorization of "the first blink" in the western confrontation with the Polish regime. The study was said to call for a "notching back" of sanctions step by step.

The basic concern of State Department and some other U.S. officials is to prevent a split in the western alliance on this sensitive East-West issue. Some officials also argue that a more flexible application of pressure, with the tangible prospect of benefits as well as pain for Poland, would be more effective than a stand-pat position.

Some of Reagan's conservative constituency as well as many in the Polish-American community oppose any shift in the sanctions, however. And some activists in Poland take the same view, even while acknowledging that the outside pressures make their lives even harsher than they might otherwise be.

The question of Poland's large-scale debt to the West has give rise to a tug of war between ideology and practicality ever since martial law, and it continues to be a central point of argument. In early 1982, the pragmatic factions in the administration, then headed by Secretary of State Alexander M. Haig Jr., beat back proposals to force Poland into default on its debts, on grounds that the western banking system could be severely damaged in the process.

Eventually private U.S. and western European banks were permitted to negotiate with the Poles on a new repayment schedule for the private bank debts, even though the western allies refused to reschedule Poland's official debt.

The result has been that Poland is paying the private banks on a gradual basis but is paying nothing on its official debt because of the absence of any agreement.

Some European officials have argued that the lack of an agreement on official debts is a hidden subsidy to Poland. Because Poland is not paying anything, the governmentally held debt is climbing, month after month, as creditor nations are forced to add the unpaid interest to the balance due.

According to Wharton Econometric Forecasting Associates, Poland owes $13.7 billion to western governments. This is a slightly more than half the $26.6 billion public and private Polish debt to the West, Wharton calculated.

The largest Polish creditors are West Germany, the United States, France and Britain, in that order. In the U.S. case Poland owes about $1.8 billion to the U.S. government and $1.1 billion to banks and businesses for a total of $2.9 billion, Wharton said.