Nigeria is postponing presidential and legislative elections until March 28 because security forces fighting Boko Haram extremists cannot ensure voters' safety around the country, the electoral commission announced Saturday in a decision likely to infuriate the opposition.

Officials in President Goodluck Jonathan's government have been calling for weeks for the postponement, saying the commission is not ready to hold what promises to be the most tightly contested presidential vote in the history of Africa's biggest democracy.

"Many people will be very angry and annoyed," Independent National Electoral Commission Chairman Attahiru Jega told a news conference Saturday night.  "I want to assure all Nigerians, no one is forcing us to make this decision, this is a very weighty decision."

He said the commission had considered holding elections outside of the four northeastern states most affected by the uprising by Boko Haram Islamic militants, but decided that the likelihood of an inconclusive presidential election would be "very, very high."

Nigerian elections traditionally are violent and several people already have died in clashes. Some 800 people were killed in protests in the predominantly Muslim north after 2011 elections when Jonathan beat former military dictator Muhammadu Buhari. Jonathan is a Christian from a minority tribe in the mainly Christian south. Buhari is a Muslim northerner.

Both men are facing off again and supporters of both are threatening violence if their candidate does not win this year's contest, one analysts say is too close to call since opposition parties for the first time formed a coalition led by Buhari.

A statement from Jonathan's party commended the postponement but blamed it on the commission, saying it is suffering "numerous logistical problems and numerous internal challenges."

Buhari's coalition said it was holding an emergency meeting to discuss the implications of "this major setback for Nigerian democracy." It appealed to all Nigerians "to remain calm and desist from violence."

Jega told reporters that national security advisers and intelligence officers have said security forces need six weeks to conduct "a major operation" against Boko Haram and cannot also safeguard the elections.

He said it would be "highly irresponsible" to ignore that advice and endanger the lives and security of electoral personnel and materials, voters and observers as well as the prospects for free, fair and credible elections.

Millions could be disenfranchised if Boko Haram continues to hold a large swath of the northeast and commit mayhem that has left 1.5 million people homeless.

The postponement comes amid a major offensive against the exremists joined by Chad and Nigerian warplanes and ground troops that has driven the insurgents out of a dozen towns and villages in the past 10 days. Even stronger military strikes involving more neighboring countries are planned.

African Union officials ended a three-day meeting Saturday in Yaounde, Cameroon's capital, finalizing details to deploy by next month an 8,750-strong force from Nigeria and its four neighbors to combat the growing regional threat posed by Boko Haram.

Nigeria's home-grown extremist group has responded with attacks on one town in Cameroon and two in Niger this week. Officials said more than 100 civilians were killed and 500 wounded in Cameroon. Niger said about 100 insurgents and one civilian died in attacks Friday. Several security forces from both countries were killed.

The insurgents also have launched three attacks within a week on Maiduguri, the biggest city in the northeast, which thousands of people were fleeing Saturday, overcrowding buses, trucks and cars with bodies and belongings.

"We fear the violence that could erupt during the elections more than the threats of Boko Haram," said Mojo Okechukwu, a 45-year-old vehicle spare parts dealer and Christian from the south who has lived in Maiduguri for 20 years.

International concern has increased along with the death toll: Some 10,000 killed in the uprising in the past year compared to 2,000 in the four previous years, according to the U.S. Council on Foreign Relations.

The United States had been urging Nigeria to press ahead with the voting. U.S. Secretary of State John Kerry visited Nigeria two weeks ago and said that "one of the best ways to fight back against Boko Haram" was by holding credible and peaceful elections, on time.

"It's imperative that these elections happen on time as scheduled," Kerry said.

The elections had been called early. Elections in 2011 were postponed until April. May 29 is the deadline for a new government to be installed.

The postponement also will give the commission a chance to deliver more voter cards: Jega said that by Friday, only 45.8 million of the 68.8 million cards needed to vote had been collected. Nigeria does not have a working postal service, though it has Africa's biggest economy.

Jonathan's party has won every election since decades of military rule ended in 1999. But the failure of the military to curb the 5-year Islamic uprising, mounting corruption and an economy hit by slumping oil prices have hurt the president of Africa's biggest oil producer and most populous nation of about 170 million.