TIRANA, Albania (AP) _ Preliminary results indicated today that Albania's Communists had picked up six more parliamentary seats in runoff elections, regaining a crucial two- thirds majority in the legislature.

Communist Premier Fatos Nano, forced into a second round by an unknown electrical engineer, was one of the six victorious Communists, the results indicated.

But the opposition Democratic Party also said it was satisfied with the results of Sunday's repeat balloting. With counting still going on in some districts, unofficial results released by the Democrats showed them winning or leading in 10 races.

Two more seats were won by a small party representing ethnic Greeks, which would give the party a total of five.

The trends shown in the Democrats' tabulation were confirmed by a statistician with the official election commission, who spoke on condition of anonymity.

The Communists, who won 162 seats in the first round of balloting on March 31, required a total of 167 seats to achieve a two-thirds majority in the 250- seat People's Assembly parliament. Winning six seats would give them a total of 168.

A two-thirds majority would give the Communists the power to pass key legislation changing the Albanian Constitution without needing the votes of any other party.

Parliament also must draw up legislation to try to pull the country out of its deep economic problems. Tens of thousands of people have fled Albania in recent months seeking a better life abroad.

A gain of 10 seats for the Democrats would give them 75, not enough to ensure the Communists must consult them.

The Communists have called for close cooperation with the opposition when parliament meets on April 15, saying that is the only way to avoid civil war in the badly polarized country.

But the Democrats have rejected the overtures and spokesman Genc Pollo repeated that stance today.

''No coalition with the Communist Party is foreseen,'' he said. ''We will try to make parliament a democratic place by playing an opposition role.''

In rejecting any participation in the government, the Democratic Party hopes that a combination of crushing economic problems and expected infighting within the Communist Party between reformers and conservatives will force new elections in as little as six months.

Democrats defeated President Ramiz Alia, the Communist Party leader, and other top officials in voting on March 31 as they took most of the urban districts. But the Communists, whose official name is the Party of Labor, won the elections on the strength of their support in the countryside.

The election of Nano in Tirana District 213 by a margin of about 54-46 percent over Democrat Sokrat Nesturi was a blow to the Democrats, but Pollo said the party was still satisfied with the results of Sunday's second round.

Six of the 10 seats it apparently won were in the countryside, he said.

''The second-round results show that we can also win in the countryside,'' Pollo said.

The polarization between city and country has led to fears that Albania will be gripped by violence in coming months.

Four people died in post-election violence last week in the city of Shkodra, where residents were protesting what they said was Communist vote- rigging.