ABEOKUTA, Nigeria -- Allegations of widespread electoral bungling and fraud -- including possible signing up of ghost voters -- grew Monday during a a 10-day voter registration campaign for Nigeria's first civilian-run elections since military rule ended.

Opposition parties charged the sign-up problems meant Africa's most populous nation risked failing a major test of its young democracy.

During the registration campaign, which ends this weekend, election overseers aim to register half of Nigeria's 120 million people for 2003 elections. Next year's vote will see the first democratically elected leader in nearly two decades -- President Olusegun Obasanjo -- contending for a second term.

The Alliance for Democracy, one of Nigeria's two largest opposition parties, complained Monday of numerous "irregularities, which can mar the entire exercise and defeat its very purpose."

Problems noted by its workers included registration stations that moved without notice, closed early or lacked forms -- thwarting would-be voters, the opposition party said.

Other problems reported by international election observers and others included stations that claimed to be signing up voters more quickly than appeared humanly possible -- while, in contrast, no registration at all was under way in some of the nation's hot spots.

Journalists reported possible fraud -- and The Associated Press watched a young male who appeared to be about 10 sign up and walk away with a card proclaiming him a registered voter.

Observers expressed particular concern about reports that registration has not even begun in some parts of central and southern Nigeria where ethnic and religious tensions are highest.

"Corruption is fast creeping into the whole exercise -- particularly in the southwest. Nobody is really sure that registration is taking place in some places," said Gani Fawehinmi, a human rights lawyer and leader of the fledgling National Conscience Party.

The election commissioner in southwest Oyo state, Ekpenyong Nsa, played down the "few lapses" brought to his attention, saying they would not affect registration overall. He claimed Nigeria's history made problems unavoidable.

"Don't forget we have been under military rule for many years and that has negatively affected our citizens," he said, adding Nigeria's widespread poverty tempts people to cheat the system.

"Poverty is corrosive on democracy," he said.

The Independent National Electoral Commission had initially planned to have completed voter registration early this year, but complained it could not do so because it lacked funding.

The absence of a national voters' list has forced the government to postpone municipal elections three times since April. Last month, the local ballot was put off indefinitely, raising questions over whether civilian authorities were capable of running the election.

Since Nigeria gained independence from Britain in 1960, all previous attempts by civilian governments to conduct elections have been aborted by military coups. The outgoing military oversaw the 1999 vote in which Obasanjo was elected.

When the current registration period ends, would-be voters will no longer be allowed to register.

Fawehinmi, the human rights lawyer, said he was unable to sign up Monday because officials had no forms.

"We are collecting reports all over. Multiple registration is not being properly prevented. They don't ask for identification. Anybody can say they are anyone," Fawehinmi said.

An international observer, speaking on condition of anonymity, reported "worrying" patterns, with some stations reporting twice as many voters as seemed possible.

Fingerprinting and filling out computerized forms takes at least five minutes, the observer said, although some turnout figures indicated officials were processing voters in less than half the time.

On Saturday, AP journalists watched officials in the southwest city of Abeokuta register a male named Dele Ogulowo, who appeared to be about 10 years old. He insisted he was 22. Election workers signed him up less than an hour after Nigeria's president surveyed the same election site.

Amadi Chike, a businessman in the northern city of Kano, said he saw men buying registration cards from newly listed voters outside one registration station.

In view of electoral workers, meanwhile, some newly registered voters were seen wiping off ink dabbed on their thumbs to prevent them from registering twice.