Nigeria has postponed the February 14 presidential election by six weeks until March 28 due to 'security concerns', the chairman of the electoral commission said.
Earlier this week a car bomb exploded as Nigeria's president Goodluck Jonathan left a party rally.
Soldiers from Chad have killed more than 200 Boko Haram militants in a battle in two Nigerian towns, the army has claimed.
Troops took on the militant group in Gambaru and Ngala, which are near the border with Cameroon.
Military sources also said Boko Haram fighters had attacked the border town of Fotokol. Agence France-Presse reports they slit residents' throats and burned down a mosque before they were beaten back.
Three bomb blasts detonated in quick succession have hit high court buildings in different areas of the Rivers state of Nigeria.
Nobody was hurt in the explosions, which police in the country believe were caused by dynamite laid by the buildings.
Police spokesman Ahmad Mohammad said the identity of the attackers was not yet known.
The commissioner of police is deeply saddened by these senseless attacks on the temples of justice in Rivers.
We must realise that violence will never be a solution to our problems.
The attacks are the latest in a string of bombings in the country, which is just two weeks away from one of its most hotly-contested elections in recent history.
One person was killed and seven others wounded when a car bomb exploded in Nigeria, just minutes after President Goodluck Jonathan left a party rally nearby.
The bomb exploded around 200 metres from the stadium in the city of Gombe, killing one bystander.
The attack comes ahead of Nigeria's presidential elections on February 14, when Jonathan - who heads up the ruling People's Democratic Party - against former military ruler Muhammadu Buhari, of the All Progressives Congress.
Experts say it is set to be the most closely-fought election since the end of military rule in 1999.
Boko Haram has launched a new attack on the key Nigerian city of Maiduguri, AFP has reported.
A fresh gun battle erupted in Nigeria between militants and troops near the airport of the northeastern city of Maiduguri, a security source and nearby resident said Sunday evening.
"I can hear sporadic gun shots and bomb explosions, I am sure the boys are back to retaliate for what was done to them this morning," Bello Muhammad, who lives about 300 metres (yards) from the airport, told Reuters.
Suspected Boko Haram insurgents launched an attack on the outskirts of Maiduguri, including the airport that is used by military and civilian aircraft, on Sunday just after midnight but were repelled by the army in the early afternoon.
Suspected Boko Haram militants launched a midnight ambush in the Nigerian city of Maiduguri, government and police sources said.
A Reuters witness said shelling could still be heard this morning. The militants began the attack at the edge of the city in the Njimtilo area.
The city is the capital of Borno state.
A man claiming to be the leader of Islamist group Boko Haram has appeared in a video to claim responsibility for a deadly attack on the Nigerian town of Baga.
The man said to be Abubakar Shekau said the attack "is just the tip of the iceberg" as he warned that the group has enough weapons to "annihilate Nigeria, not to mention Cameroon".
Local officials put the death toll in Baga as high as 2,000 but the Government said 150 people were killed when insurgents stormed a military base in early January.
The bearded man is surrounded by masked fighters in the video, who show off an array of weapons allegedly taken from the base during the attack.
Troops from Chad join in the battle against the terror group after it kidnapped 80 people including 50 children from Cameroon.Read the full story ›
A suicide bomber drove a car packed with explosives into a busy bus station in the northeast Nigerian town of Potiskum on Sunday, killing four people and wounding 35, police said.
There was no immediate claim of responsibility for the attack, which bore the hallmarks of Islamist militant group Boko Haram.
"The information I have is that the car was pretending to be scouting for passengers," Yobe state police commissioner Danladi Marcus told Reuters news agency by telephone.
"Five people including the bomber were killed in the attack with about 35 others receiving treatment for various injuries at Potiskum General Hospital."