DOUALA, CAMEROON — AN open truck with soldiers standing in the back rolls down a main street, past a cinema. A few blocks away, several buildings are burned out; another has had its windows smashed. Inside this port city's government radio building, the station director opens a drawer full of death threats.The struggle for democracy has included days of violence in Cameroon, a coastal nation of nearly 12 million on the Atlantic Ocean, southeast of Nigeria. Opposition groups in a handful of African countries have managed this year to dump their dictators and elect leaders without a civil war. But more than a year of sometimes violent pressure on the authoritarian regime of President Paul Biya has produced only deadlock, say diplomats, government officials, and opposition leaders interviewed in Douala, the economic heart of the country. "There's a stalemate," says a Western diplomat. "There's a need for creative thinking and a willingness for both sides to not stand on their pride and [to] think [instead] in terms of negotiations." Several people were killed and hundreds of students, journalists, and others detained last year by police during demonstrations for reforms that include multiparty elections to replace Cameroon's one-party system. Amnesty International, the human-rights group, reported that detentions without trial during the Biya regime include the sham trials last year of two activists apparently tortured for trying to set up two new political parties. Late last year, Biya agreed to allow multiparty elections, freed political prisoners, and gave greater freedom to the press, though retaining Cameroon's censorship law. But opponents claim some of the new political parties springing up are government creations. Temporary detention of some opposition leaders has continued. Several newspapers, including Le Messager, were banned recently for failing to submit for censorship articles critical of Biya. In June, Biya refused the main opposition demand: a "sovereign" national conference of opponents and government representatives. Opposition leaders explain that by "sovereign" they mean that the conference would assume supreme legal authority, organize a new government and pass new election laws. Biya's critics charge that current election rules do not guarantee a free choice. SUCH a conference would likely shift many presidential powers to an interim government headed by a prime minister, says Jean Jacques Ekinda, an opposition official. In a June speech to the nation, Biya branded the idea of a sovereign national conference as unconstitutional. He said delegates to such a conference would have no electoral mandate to create a new government. On the day of the announcement, riots broke out in several cities, including Douala. Sporadic clashes with police have continued. In response to the unrest, Biya has assigned military leaders to seven of 10 provinces where there have been signs of significant opposition. This, however, raises the risk of a military coup, some opposition leaders say. Mr. Ekinda, who until earlier this year was a member of the ruling party, the Cameroon People's Democratic Movement (CPDM), says he quit when he realized Biya was not going to make any more concessions. Ekinda alleges that the Biya government is "a regime of tyranny." Biya, he says, has lost control of the country to corrupt aides who squander state funds. Biya has agreed to hold parliamentary elections, probably in November or December, and to have international observers at the polls, says Linus Onana, director of the government radio station in Douala, and an outspoken Biya defender. "If the opposition gains the majority, the president will probably resign," Mr. Onana says. Biya is willing to hold a nonsovereign national conference "to reexamine the electoral code," he adds. Some opposition leaders say citizens will boycott elections unless a sovereign national conference is held first. Biya was prime minister from 1975 to 1982 when Cameroon's first president, Ahmadou Babatoura Ahidjo suddenly resigned and handed power over to him. As sole presidential candidate in 1984 and 1988, Biya won more than 99 percent of the vote both times. Legislative elections in those years resulted in the defeat of 50 percent and 85 percent, respectively, of the incumbents. Onana claims "the president is still strong." He blames much of the opposition on a power struggle between two tribes, the president's Beti tribe in the south and the Bamil in the west. Opposition leaders come from many parts of Cameroon, including the majority French-speaking and minority English-speaking areas. But some of the strongest opposition is in the Bamil region.