ABUJA (Reuters) - Nigeria postponed parliamentary elections until Monday after voting materials failed to arrive in many areas, a major blow to hopes of a break with a history of chaotic polls in Africa's most populous nation.
Voters had trooped early to polling stations across the country of 150 million, eager for a ballot less tainted by fraud and violence than 2007 elections that lacked credibility in the eyes of Nigerians and international observers.
The postponement brought bitter disappointment.
"Nigeria has not changed and today we have seen that," said Kingsley Eze, 23, an amateur jazz musician in Port Harcourt, hub of the oil industry which provides most of Nigeria's exports.
Confusion added to the frustration in Nigeria's biggest cities -- the commercial hubLagos in the south and Kano in the north -- where voting went ahead in some places because election materials had arrived on time.
"It only tells how grossly incompetent we are about nearly everything," complained computer engineer Bayo Ayodele in Lagos.
"I bet you most people who were disappointed will not come back on Monday... After all, our votes don't usually count."
The parliamentary polls are seen as a test of whether Nigeria can break with a history of flawed ballots. Presidential elections are due in a week's time and governorship votes in the 36 states a week after that.
Successful elections would be another fillip for foreign investment in Nigeria and across fast-growing Africa as well as strengthening Nigeria's international clout.
But failure could raise questions about how well-entrenched democracy is, more than a decade after the end of military rule.
President Goodluck Jonathan, favorite to win re-election on April 9, was among those to discover on Saturday that voting materials had not reached his home region, in the oil-producing Niger Delta. It was the same across much of Nigeria.
The head of the Independent National Electoral Commission (INEC) blamed the delay on the failure of a supplier to get materials shipped on time.
"The decision we have taken is weighty indeed but it is an important step in further ensuring the credibility of the 2011 elections," Attahiru Jega said in a televised address, adding that he was confident all would be in place on Monday.
Jega made no suggestion of any delay to the elections for the presidency or for state governors.
The electoral commission has put in place tougher measures to prevent cheating and intimidation, which raised such doubts over the last elections in 2007 that foreign observers said they may not have reflected the will of the people.
Observers from the Commonwealth, a group of mostly former British colonies, said they hoped the electoral commission would ensure there were no more problems after the postponement.
"We also call for calm and restraint on the part of all stakeholders, so that the elections can still take place in an atmosphere of peace and order," said Festus Mogae, the former president of Botswana leading the observer team.
Little violence had been reported on Saturday beyond some shooting in the volatile oil-producing Niger Delta.
The build-up to the polls had risked exposing ethnic and religious fault lines in the country roughly split between a Muslim north and Christian south but with sizeable minorities living in both regions.
There had been isolated bomb attacks on campaign rallies, riots on the edge of theNiger delta and sectarian violence in the north and center, but elsewhere observers had noted less thuggery and intimidation than in the run-up to 2007 polls.
The parliamentary elections are not as significant as those later this month, but they are fiercely contested by candidates who stand to win a pay package whose allowances alone top $1 million a year. Many Nigerians subsist on less than $2 a day.
Jonathan's ruling People's Democratic Party (PDP) is expected to see its parliamentary majority reduced. The PDP holds more than three-quarters of the 360 seats in the House of Representatives and of the 109 in the Senate.
(Additional reporting by Reuters reporters in Abuja, Lagos, Port Harcourt, Yenagoa,Maiduguri, Bauchi, Kano, Ibadan, Onitsha; Writing by Nick Tattersall; Editing by Matthew Tostevin)