The indications were that voting largely followed entrenched ethnic patterns. The Christian-dominated Ibo in the east tended to support the National Republican Convention (NRC), as did the Hausa in the predominantly Muslim north. In the west and the south, the Yoruba tended to support the SDP.
The strong evidence of voting along ethnic lines is expected to disappoint President Ibrahim Babangida's government, which has sought unsuccessfully to rid the country of ethnic tensions.
In Lagos state, the SDP won the state's three Senate seats and 14 of the 15 in the House of Representatives, national radio said, citing the National Electoral Commission. The other Lagos seat in the House was won by a member of the NRC.
The state of Lagos, like the rest of south west Nigeria, has been solidly SDP since local government elections in December 1990. But following internal quarrels, the rival NRC's candidate won the state's election for governor in December 1991.
The elections herald a return to civilian rule in Africa's most populous country after nine years of military dictatorship. But the polls, contested by two parties created and funded by the military government, have generated little enthusiasm.
The two legal parties, NRC and the SDP, have focused more on making vague promises of a better life than on the issues of soaring inflation and ethnic tensions, that have dominated Nigerian politics in recent months. The parties' silence on the eruption of anti-poverty protests and ethnic violence in May, and on the arrests and subsequent release of prominent human rights activists, including Dr Beko Ransome-Kuti and Chief Gani Fawehinmi, indicate their isolation from the public's main concerns.
Despite slick media campaigns financed by the state, the parties' lack of criticism of the government's handling of recent crises has reinforced a common view that they are the creatures of the military administration. A drive to purge the official voting list of millions of 'ghost' voters in the run-up to the elections was met with apathy. Serious opposition to President Babangida's government came not from the political parties but from the human rights community, university students and the nation's lawyers.
Many doubts hang over the exact role of the assembly, a US-style legislature of a 589-member house of representatives and a 91-seat senate, between now and when General Babangida hands over to an elected civilian government in January. There seems little chance that the armed forces' ruling council, which rules through military decree, will dissolve before the army's return to the barracks. This indicates that the elected national assembly may be little more than a debating club until next year.
Indeed, the importance of Saturday's vote is seen by many as a pointer to the December elections for president, in which at least 80 candidates, spending tens of millions of pounds, are competing. The NRC won a small majority in elections for governor last December while the SDP, then badly divided, gained a majority of the 30 state assemblies.
Reflecting a fear of renewed violence, the Nigerian authorities deployed up to 100,000 security forces during the elections. Voting was carried out by the controversial 'open ballot' in which voters queued up behind the party of their choice. Henry Nwosu, the chairman of the national electoral commission, argued that the 'open ballot' was the only way to avoid the widespread rigging that afflicted previous Nigerian elections.
However, the 'open ballot' drew criticism from the NRC, labour activists and the Campaign for Democracy, a coalition of human rights, women's and student groups that emerged as a forceful opposition movement to the Babangida government. 'The system is primitive and undemocratic,' said Ojoha Odah, the assistant secretary of the Nigerian Labour Congress. 'No civilised society ought to go near it even with a long pole.'
Nigeria, a big oil exporter, has been beset by religious and tribal rivalries since independence from Britain in 1960. Both previous civilian administrations in 1960- 66 and 1979-83 were toppled by Nigeria's politicised military amid charges of rampant corruption and mismanagement.