Seventy-one people died in a bomb blast in a packed bus station in Nigeria's capital Abuja on Monday -- the deadliest attack yet to strike the city -- with the president blaming the explosion on Boko Haram Islamists.

The bomb, which also injured 124 people, rocked the Nyanya station on Abuja's southern outskirts at 6:45 am (0545 GMT) as it was filled with morning commuters, leaving body parts scattered across the terminal and destroying dozens of vehicles.

Previously, much of the recent violence by the Boko Haram insurgency has been in the remote northeast, though some have targeted the central capital.

The United States condemned the attack, denouncing it as "senseless" and called for a full investigation into it.

"We are outraged by this senseless act of violence against innocent civilians," State Department spokeswoman Jen Psaki told reporters.

"We continue to stand with the Nigerian government and people as they grapple with violent extremism," she said, also condemning a series of attacks on three villages in Borno State over the weekend.

The South African government, in a statement, also condemned the attack, saying that it believed that "terrorism, in any form and from whichever quarter, cannot be condoned".

This major bombing, just a few kilometres (miles) from the seat of government, will raise further doubts about Nigeria's ability to contain the Islamist threat it is battling.

The explosion "emanated from a vehicle" parked within the station, said Charles Otegbade, head of search and rescue at the National Emergency Management Agency.

National police spokesman Frank Mba put the toll at 71 dead and 124 injured. The wounded were being treated in area hospitals.

Visiting the site, President Goodluck Jonathan vowed that Nigeria would overcome the brutal insurgency being waged by Boko Haram, blamed for killing thousands across the north and centre of the country since 2009.

"The issue of Boko Haram is quite an ugly history within this period of our own development," Jonathan said. "But we will get over it... The issue of Boko Haram is temporary."

The Islamists, who say they want to create a strict Islamic state in northern Nigeria, have previously set off bombs in and around the capital, including a 2011 car bombing at the United Nations headquarters that killed at least 26 people.

'Charred bodies removed'

Monday's explosions at the bus station left a hole roughly 1.2 metres (four feet) deep and spread debris across the compound, an AFP reporter and witnesses said.

"I saw bodies taken away in open trucks," said witness Yakubu Mohammed, describing grisly remains that "were burnt and in pieces".

Nyanya is a densely populated suburb of Abuja, filled with government and civil society workers who cannot afford the city centre's exorbitant rents.

Bus parking zones have been among Boko Haram's preferred targets, including a bombing at a terminal in the northern city of Kano last year that killed more than 40 people.

'Security crackdown'

Jonathan, who is expected to face a tough re-election battle next year, has faced intense criticism over the continuing Boko Haram violence.

With the recent unrest concentrated in the northeast, the president had been able to claim that progress was being made in the battle against the Islamist rebels.

But an escalation of attacks in or near Abuja would pile further pressure on the embattled president.

Prominent targets within Abuja have been locked down since the UN bombing and checkpoints are set up daily on major roads throughout the city.

Security measures are however less rigid in areas outside the city centre.

Following Monday's attack, police chief Mohammed Abubakar ordered officers "to intensify surveillance on all vulnerable targets within Abuja", Mba said.

But a temporary security crackdown will not be enough to repair Jonathan's declining credibility in the Boko Haram conflict, according to Adetokunbo Mumuni of the Socio-Economic Rights and Accountability Project.

Last May, the military launched a massive offensive to crush the Islamist uprising and has described Boko Haram as being in disarray and on the defensive. But the success of that campaign was being questioned after Monday's bloodshed.

"It is obvious the attack is aimed at sending a message to the government that the insurgents are very much around and can strike at any time they choose," said Abubakar Tsav, a retired police chief and security analyst.

Experts warn that force alone cannot stem the bloodshed and have called for a major outreach to dejected and deeply impoverished youths from the north who fill Boko Haram's ranks.

Nigeria is Africa top oil producer and largest economy, but more than 80 percent of its 170 million people live on less than $2 per day.

Analysts say that the Boko Haram unrest has partly stalled economic growth and scared away potential investors.

"The government is doing everything to make sure that we move our country forward," Jonathan affirmed after the attack.

The US State Department has offered a $7 million reward for information leading to the arrest of Boko Haram leader Abubakar Shekau.