Ilias Alevras, 70, is Greek, but he has spent the past 33 years in Romania as a political exile.

The mild-spoken Alevras is a Communist, one of the tens of thousands who fled to the East Bloc after the bloody 1946-49 civil war in which the conservatives won charge of Greece's post-war political fortunes. Since then, the Communist exiles, stripped of Greek citizenship and largely barred from returning, have come to symbolize political discrimination in Greek life.

Now, under a mass amnesty declared over Christmas by Premier Andreas Papandreou, Alevras and an estimated 35,000 political refugees like him can recover their citizenship, simply by filling out a form, and come home.

Greece divided into left- and right-wing camps during World War II, when rival Communist and rightist guerrilla groups set up to resist the Nazi occupation. After 1945, Greece became an early battlefield in the Cold War as Stalinist Communists fighting the right -- which had the support of Britain and the United States -- for control of the country.

The civil war cast a long shadow, with vendetta-style hatreds that still linger on the family level. It is estimated that the war cost Greece 80,000 lives. About 20,000 Greek Communists were sentenced for crimes against the state, and more than 5,000 received death or life sentences. Many Communists fled across the Albanian border as the fighting wound down, while others were exiled after imprisonment.

Whether many of the exiles will choose to come home, and whether their return will rekindle the bitter but dormant passions of the civil war are questions being raised by Papandreou's action.

The Socialist's choice of Christmas for the amnesty move has caused the conservative New Democracy opposition party to accuse Papandreou of attempting to distract the electorate from Greece's economic problems.

The unspoken implication is that Papandreou is at the same time trying to curry favor with the modern-day Communist Party, whose support he needs if his austerity program for 1983 is to succeed.

New Democracy, in contrast with all the left-of-center opposition parties, had also criticized Papandreou's prompt post-election step last year to recognize formally the outlawed Communist groups that had spearheaded wartime anti-Nazi resistance. Most of the political exiles belonged to these groups.

The elderly Alevras is one refugee who intends to take advantage of the amnesty. "Yes, I will definitely come back. I've spoken to other friends in Romania over the phone and this is an occasion of relief and joy for all of us," he said in an interview on Greek state radio. He was in Athens for Christmas under a special law which since 1974 has permitted some exiles to visit.

Alevras added, "We have suffered a lot. We have been able to keep the Greek language alive and teach it to our children thanks to special schools. But Romanian customs and traditions are very different from ours. We have been intensely homesick."

However, the image of waves of still dedicated -- if nostalgic -- Communists flooding back to Greece, which is troubling to some, may not materialize.

Older exiles like Alevras face the issue of pension and other social security payments, which they currently get from their host countries. These countries, especially the Soviet Union, where the largest Greek exile community is found, are reluctant to spend valuable foreign exchange to keep up these payments to expatriates.

Papandreou has suggested that the Greek state could undertake this expense, receiving an equivalent value of imports from these countries. By that formula, Athenians could come to owe a renewal of their Hungarian-built bus fleet to the return of the Communist refugees. But no agreement has yet been reached.

Housing and employment will also pose a problem--particularly at a time when the ranks of the Greek unemployed, like those elsewhere, are growing.

Without advance arrangements on these practical issues, life in the home country can be bleak, as some exiles found on returning under a case-by-case statute introduced by the New Democracy government that followed the 1973 collapse of the colonels' junta.

A second-generation political exile, Lambros Koumantanos, 26, said on the radio show, "I came back to Greece in 1978, from Poland. I was an art student there. But since I got back I've had to work at any kind of odd job just to survive.

"I always felt I had to come back to Greece, that this is my country. But the government now should be aware of the practical problems and try to help resolve them," he added in heavily accented but correct Greek, learned in Poland.

If and when the Communists do come back, few observers foresee a large-scale revival of past hatred. Analysts note that the conservatives attacked Papandreou for the allegedly demagogic style and timing of his amnesty, not the actual decision to let the exiles return. They also stress that the process had started under the New Democracy administration.

These observers agree that the most immediate and tangible result of Papandreou's gesture is, rather, the unanimous praise that it drew from all the left-wing opposition parties, most importantly the Communist, which through its power in the trade unions holds the key to labor cooperation in Socialist Greece.

It remains to be seen whether this praise will translate into labor support or at least tolerance for the wage freeze and belt-tightening economic measures which the Socialist government has planned.