Nigeria's Islamist militant group Boko Haram has declared "total war" on the West African country and the situation "must be handled with all the seriousness it deserves," Senate President David Mark said.

"The escalation of violence and the heinous crimes daily perpetrated by insurgents and terrorists including the declaration of a caliphate has reached alarming proportions," Mark told lawmakers in the capital, Abuja, Tuesday at the reopening of parliament after its summer break. The insurgents sought to humiliate the nation when they "brazenly hoisted their flags to confirm their assault and affront on our collective will."

Nigeria's parliament is due to debate President Goodluck Jonathan's July request to borrow $1 billion for additional equipment to fight the rebellion, which according to Human Rights Watch killed more than 2,000 people in the first half of this year. Tens of thousands have been displaced from their homes by the violence.

The United Nations Refugee Agency said Tuesday it was calling on donors to urgently provide $34 million to pay for lifesaving assistance to more than 75,000 people who have since last year fled the violence in northeast Nigeria by crossing into Chad, Cameroon and Niger.

"Aid agencies expect that the number of people fleeing to the three neighbouring countries could exceed 95,000 by the end of the year," UNHCR spokesman Babar Baloch said in remarks e-mailed by its West Africa office in Dakar, Senegal.