Kano - Islamist group Boko Haram has vowed to make voting impossible in Nigeria's upcoming election after a spate of deadly attacks in the country's violence-wracked northeast.
The group's leader Abubakar Shekau said in a new video posted on Twitter late on Tuesday evening that his fighters would disrupt polling in Africa's most populous nation scheduled for March 28.
"This election will not be held even if we are dead. Even if we are not alive, Allah will never allow you to do it," he said in the Hausa language widely spoken in northern Nigeria.
Shekau also claimed responsibility for a large-scale attack on the northeastern city of Gombe last Saturday where leaflets were dropped warning people not to vote.
The latest threats came as the embattled head of Nigeria's electoral body faced senators in parliament to explain his decision to delay the election by six weeks.
Attahiru Jega, president of the Independent National Electoral Commission (INEC), has been criticised for agreeing to the postponement on security grounds.
National security advisor Sambo Dasuki recommended pushing back the date from February 14 to give troops in a regional offensive against Boko Haram more time to secure and stabilise the northeast.
The deployment would leave soldiers unavailable to provide security on polling day, he said.
But Dasuki's six-week deadline to effectively crush the militants has been seen as unrealistic, even if it allows INEC more time to distribute more ID cards to the 68.8 million registered voters.
- Increased violence -
The insurgents, whose six-year rebellion has claimed more than 13,000 lives and left more than a million homeless, on Tuesday gave a renewed indication of their resilience.
Two suicide attacks -- one at a checkpoint near Biu in Borno state and another hours later in a restaurant in Potiskum in Yobe -- killed at least 38.
Many of the victims at the first were children.
The bombings were the latest in an increase in violence since the start of the year and linked to the elections, which Boko Haram views as un-Islamic.
Militants have captured swathes of territory, making voting impossible in many areas of Borno, Yobe and Adamawa states and raising fears about the validity of the final election result.
Mounting concerns about the threat Boko Haram poses to regional security have increased and galvanised Nigeria's neighbours into joining the counter-insurgency.
Chadian troops deployed to Cameroon to help fight increased attacks in the country's far north, while Niger has agreed to send soldiers to help the fight-back.
On Tuesday, thousands took to the streets of Niamey to protest against the group and President Mahamadou Issoufou vowed: "Niger will be the death of Boko Haram."
But Shekau again dismissed the regional force in the new video, threatening Issoufou and Chad's President Idriss Deby.
- Chadian advance -
Boko Haram, which wants to create a hardline Islamic state in northeastern Nigeria, this month opened up two new fronts in the bitter conflict, attacking border regions in Niger and Chad.
But the Chadian military, which recently regained control of the Nigerian town of Gamboru on the border with Cameroon, on Tuesday evening said they had pushed further into Borno state.
Two Chadian soldiers and several Boko Haram fighters were killed in violent clashes around Dikwa, some 50 kilometres (31 miles) southwest of Gamboru, on Tuesday afternoon.
A militant camp, which is near the group's stronghold in the Sambisa Forest, was overrun, Chadian military sources said.
Chad's presence well inside Nigerian territory is a first and may indicate a strategy to push on further to rebel-controlled areas to assist the beleaguered Nigerian military.
Boko Haram fighters on Monday evening razed the Borno town of Askira Uba, 25 kilometres south of Chibok, from where more than 200 schoolgirls were kidnapped in April last year.
Residents said soldiers deployed in the town since September last year refused to mobilise. There have been multiple reports of Nigerian troops failing to engage the militants in recent months.