Nigeria has little chance of holding credible elections because with less than 10 days to go, voters don't know who the candidates are or where and how to vote, a home-grown observer mission said on Thursday.
The Transition Monitoring Group said the electoral body, under influence from the government, had caused confusion to keep voters in the dark about their rights and allow candidates chosen by the outgoing administration to win more easily.
"These crises are contrived to force a determined outcome," said Innocent Chukwuma, chairman of the group which plans to deploy 10,000 monitors across Nigeria during the polls.
"It is very doubtful if the current situation can be salvaged as there is very little time left to the elections."
On April 14, Nigerians are due to vote for state governors and members of state houses of assembly.
On April 21, they elect the president and members of the National Assembly.
The polls should deliver the first handover of power from one elected president to another in Africa's most populous nation, which returned to civilian government in 1999 after three decades of almost continuous army rule.
President Olusegun Obasanjo was elected in 1999 and won a second term in 2003, but the constitution does not allow him to seek a third term.
The criticism from the Transition Monitoring Group, which observed the 1999 and 2003 polls, comes a day after US-based Human Rights Watch voiced similar concerns about violence and political meddling.
Information Minister Frank Nweke rejected the Human Rights Watch report on Thursday, denying that the government was interfering with INEC.
He said the electoral body was well prepared to hold free, fair and credible elections.
A panel of former heads of state and state governors, including two opposition presidential candidates, visited the operations hub of the electoral body on Wednesday and expressed confidence in the preparations.
"We hope that those in the field will be able to perform but (the visit) has given us a lot of confidence," said the leading opposition presidential candidate, Muhammadu Buhari.
"Anyone who has seen the investment made for a free and fair election will not fail to be impressed." But the Transition Monitoring Group said preparations for the elections were a "shambles".
Chukwuma said a shoddy voter registration had led to "massive disenfranchisement" of voters.
He said the Independent National Electoral Commission (INEC) had broken its own promise to display the register everywhere in Nigeria, so that voters were unable to contest any incorrect or missing data.
"There is absolutely no information coming out of INEC about the voting procedures, the locations of polling stations. No one knows what the ballot papers will look like," he told a news conference in the capital Abuja.
Chukwuma said that the level of preparedness was worse than it was before the 1999 elections and after eight years in power, a civilian administration was doing worse than the military, who oversaw those polls.
He also said election-related violence was worse than in 2003, when both local and foreign observers said the polls were marred by widespread fighting and intimidation.