Heavy rains that caused a dam to overflow in southwestern Nigeria and led to houses being submerged has killed 20 people and displaced thousands, an emergency management agency spokesman said on Sunday.

"Twenty confirmed dead," said Yushau Shuaib of the flooding in the city of Ibadan. "A dam overflowed its boundary ... It's a very serious situation."

A suicide bomb blast rocked the U.N. compound in the Nigerian capital Abuja on Friday, killing at least 18 people, leaving others trapped and blowing out large areas of the building, officials said.

Witnesses reported that the bomb went off after a suspect rammed a car through the front gate. Parts of the first two floors of the building were blown out and rescue workers scrambled to rescue those left inside.

Religious-linked violence and abuse rose around the world between 2006 and 2009, with Christians and Muslims the most common targets, according to a private U.S. study released Tuesday.

"Over the three-year period studied, incidents of either government or social harassment were reported against Christians in 130 countries (66 percent) and against Muslims in 117 countries (59 percent)," said the Pew Research Center's Forum on Religion and Public Life study.

At least 25 people were killed during a Nigerian military raid after a bomb blast blamed on Islamists and many others have been reported missing, a statement from Amnesty International said Friday.

The statement referred to an incident last weekend in the northeastern city of Maiduguri, which has seen a wave of attacks attributed to an Islamist sect known as Boko Haram and where hundreds of troops have been deployed.

Authorities stepped up security Monday as they launched a probe into multiple attacks that killed 20 people in northeastern Nigeria, including a bomb blast at a police barracks.

The police barracks bombing killed at least 10 people Sunday evening in the troubled city of Maiduguri where Islamists are active.

A radical Islamist sect has claimed responsibility for Nigeria's first suicide bombing, saying the attack that killed two at Abuja's police headquarters targeted the country's police chief.

"We are responsible for the bomb attack on the police headquarters in Abuja which was to prove a point to all those who doubt our capability," the group known as Boko Haram said after the attack late Thursday.

Gunmen killed a prison warden and a traditional chief in Nigeria's northern state of Bauchi where a radical Islamist sect is active, police said Wednesday.

A neighborhood leader who also works as a prison warden, Ibrahim Ali Figidi, was gunned down outside his house by two men who fled on a motorcycle in the typical hit-and-run style of the Boko Haram sect.

So what do you get in Nigeria when you take Sunday, God's Gift, Whoknows, Noisy Place and, of course, Goodluck? Could be a family gathering.

This Sunday's inauguration of President Goodluck Jonathan will do more than officially bring an end to a landmark election period in Nigeria.

Three days of rioting linked to last month's presidential elections in Nigeria left at least 800 people dead, Human Rights Watch said on Monday.

"Deadly election-related and communal violence in northern Nigeria following the April 2011 presidential voting left more than 800 people dead... The victims were killed in three days of rioting in 12 northern states," the New York-based rights watchdog said in a statement.

Syrian President Bashar al-Assad signed a decree to lift almost five decades of draconian emergency rule on Thursday, as a protest movement that has rocked his regime called further demonstrations.

Assad, who has been in power since he replaced his father 11 years ago, issued the order to scrap the state of emergency along with separate decrees to abolish the state security court and to allow citizens to protest peacefully.