Nigeria's ambassador to the US has criticised Washington for refusing to sell his government "lethal" weapons to fight militant Islamists.
Nigeria needed support to deliver the "killer punch", not "light jabs" against the Boko Haram group, Adebowale Ibidapo Adefuye said.
His comments came as the militants seized the north-eastern Mahia town.
The US has previously ruled out heavily arming the Nigerian military because of its alleged poor human rights record.
Meanwhile, Nigeria's President Goodluck Jonathan has formally declared himself as the governing People's Democratic Party's candidate (PDP) presidential candidate for February's election at a colourful ceremony in the capital, Abuja.
He called for a minute of silence for the 46 teenage boys who were killed in Monday's suicide bombing at a school in Potiskum town in Yobe, one of the three north-eastern states under a state of emergency because of Boko Haram's insurgency.
The attack has highlighted the depth of the crisis escalating in the north-east, the BBC's Nigeria correspondent Will Ross reports.
But the politicians of all parties appear more focused on the pursuit of power in oil-rich Nigeria and that is playing right into the hands of Boko Haram, he says.
Government soldiers have been accused by rights groups of carrying out many atrocities, including torturing and executing suspects.
US laws ban the sale of lethal weapons to countries whose military are accused of gross human rights abuses.
But Mr Adefuye said the accusations were based on "half-truths", rumours and exaggerated accounts, which were being spread by political opponents ahead of the elections.
"The US government has up till today refused to grant Nigeria's request to purchase lethal equipment that would have brought down the terrorists within a short time,'' Mr Adefuye told members of the New York-based Council on Foreign Relations.
"We find it difficult to understand how and why, in spite of the US presence in Nigeria with their sophisticated military technology, Boko Haram should be expanding and becoming more deadly,'' he added.
Mr Adefuye said Boko Haram was Nigeria's equivalent of the Islamic State group, and threatened the nation's "territorial integrity".
"There is no use giving us the type of support that enables us to deliver light jabs to the terrorists when what we need to give them is the killer punch," he said.
"A friend in need is a friend indeed. The true test of friendship is in times of adversity," he added.
Who are Boko Haram?
- Founded in 2002
- Initially focused on opposing Western education - Boko Haram means "Western education is forbidden" in the Hausa language
- Launched military operations in 2009 to create Islamic state
- Thousands killed, mostly in north-eastern Nigeria - also attacked police and UN headquarters in capital, Abuja
- Some three million people affected
- Declared terrorist group by US in 2013
Boko Haram has recently changed tactics, focusing on holding on to territory rather than launching hit-and-run raids.
It has now captured Mahia to add to the territory the group already controls, our reporter says.
It is a small town near Mubi, the second largest town in Adamawa state, which Boko Haram last week renamed Madinatul Islam - City of Islam.
In April, Boko Haram sparked global outrage by abducting more than 200 girls from a boarding school in Chibok town in Borno state.
Boko Haram leader Abubakar Shekau has dismissed government claims to have agreed a ceasefire, under which the girls would be released.
He says the children have converted to Islam, are learning to memorise the Koran and have been married off.
The US, China, UK and Israel had promised to help Nigeria track down the girls.