Estonians protest Soviet-Nazi pact and press for autonomy. Anticipating emotional demonstrations in the Baltic republics today, Communist Party officials have been making significant concessions to nationalist sentiment.

Authorities here have made sweeping concessions to nationalist Estonians on the eve of mass demonstrations planned for today, the anniversary of a pact that allowed Moscow's 1940 annexation of this and two neighboring Baltic states. For the first time in the Soviet Union, the secret protocols of the 1939 Molotov-Ribbentrop Pact between Stalin and Hitler, have been published here by the Estonian- and Russian-language press. The publication of this ``nonaggression'' pact raises questions about the legitimacy of the Soviet annexation.

On a recent radio program in Estonian, a caller asked whether the publication of the protocol now entitled the Estonians to ask the Soviets to leave.

``We have to take into account the existing political realities,'' came the diplomatic reply.

In other recent concessions, the republic's Communist Party has legalized the national colors of the Estonian flag and agreed to change to Estonian time - one hour behind Moscow. The party is also considering proposals for Estonian to be enshrined in the republic's Constitution as the official language, and for establishing Estonian citizenship which could also embrace Estonians living abroad.

Today's rallies - planned in neighboring Latvia and Lithuania as well as Estonia - have been authorized by the Communist Parties for the first time.

The Popular Front, a new political movement outside the Estonian Communist Party (although including some party members), is widely considered to have been instrumental in pushing through the reforms. The group was formed in April while the Communist Party was in a ``crisis of confidence'' according to a senior party official. The front has also managed to push through a far-reaching economic autonomy plan for the republic, which now has Moscow's blessing.

The scheme, which is to come into force next January, will cut the republic's links to the central ministries in Moscow, and establish market-oriented economic reforms in industry and agriculture. At present, only 10 percent of Estonian industry is locally controlled.

There have also been calls for Estonia to become a special economic zone along the lines of the Chinese model. Once again Moscow seems unexpectedly favorable.

Popular Front spokesman Edgar Savisaar denies that the economic autonomy is a first step toward taking Estonia out of the Soviet Union. Estonia was an independent state from 1922 to 1940.

``Our slogan is: We want a sovereign Estonia inside the Soviet Union,'' he said in an interview. Mr. Savisaar, a Communist Party member who spearheaded the drive for economic autonomy, has just been named to a ministerial post and is to be responsible for implementing economic autonomy in Estonia.

But for many Estonians, political independence is the ultimate goal, and they say that Moscow has agreed to the idea of economic autonomy without really knowing what was involved.

Estonian economist Tiit Made says that Soviet leader Mikhail Gorbachev decided to back economic autonomy in Estonia because his restructuring efforts known as perestroika have so far failed to produce results.

``We have glasnost (openness), but we don't have perestroika. And after Armenia, he must have thought that we don't need more problems in the Baltic states, so let them try it,'' Mr. Made says.

Armenia's economy was hit by five months of nationalist strikes and unrest in February.

Savisaar insists that the Popular Front, which on June 17 held the largest rally in Estonian history attended by more than 150,000 people, is not seeking to substitute itself for the Communist Party, which is still the country's sole legal political party About one third of the movement's supporters are from the reforming wing of the party.

Savissar argues that the Popular Front is a movement, not a party, even though it plans to field candidates at the next elections along with supporters of the republic's Greens ecological movement.

For 38-year-old Savisaar and his supporters, changing the republic's leadership is a necessary step on the path to reform. The front is to hold its founding congress on Oct. 1 and 2. Savisaar will then have to take a back seat, as Popular Front leaders must relinquish their positions if named to party or government posts, to avoid a conflict of interest.

The movement has also organized three rallies today in different Estonian cities to mark the anniversary of the Molotov-Ribbentrop Pact.

``We will judge the pact,'' Savissar says, adding that Moscow historian Yuri Afanasyev is to be a guest speaker along with writers from Moscow.

The party itself is not planning any official demonstration on Tuesday, but, unlike last year, is likely to tolerate the unofficial rallies.

Savisaar attributes the party's abrupt change of attitude in recent months to ``perestroika in Moscow.''

Russian residents of Estonia, meanwhile, are reacting with alarm to the latest developments here. Non-Estonians comprise up to 40 percent of this republic's 1.5 million people.

The non-Estonians were uninformed for a long time about the aims of the Popular Front and economic autonomy, because the local Russian-language newspapers did not report the ideas being debated in the Estonian-language news media.

In apparent response, a Russian ``internationalist movement,'' with some 2,500 supporters, held its first conference in Tallin last week. The 150 delegates, in the presence of numerous Estonian observers, discussed an action program to oppose any special privileges being granted to Estonians.

The Russians are particularly concerned about plans to make Estonian the official language and suggestions that non-Estonians should be deported.