A British-born citizen who once served in the Nigerian army has been arrested on suspicion of being a ringleader of the Islamist militants who killed 105 people in two bomb blasts in Nigeria last month.

Aminu Sadiq Ogwuche, in his 30s, was arrested this week in Sudan after Interpol issued an international arrest warrant for the former lance corporal who is believed to have played a key part in the Boko Haram bomb attacks.

The group, which bombed the capital, Abuja, last month with rush-hour devices in the packed suburb of Nyanya, is the same one behind the abduction of 300 schoolgirls in a remote village in the country.

Ogwuche, in his 30s, is being detained ahead of his extradition to Nigeria from Sudan's capital, of Khartoum, where he was studying Arabic at the International University of Africa.

His duties there included luring new recruits with promises of studying in the east African nation, which has traditionally been an Islamic centre for learning and culture, according to a Nigerian counter-terrorist official.

In 2012, a group of almost 100 recruits who believed they were heading to Sudan for Islamic studies were instead transported westwards across the Sahara to a terrorist training camp in Algeria, the official added.

Nigerian intelligence officials have long suspected jihadist extremists of training with Islamist groups in both Somalia and Sudan, where al-Qaida formerly had a strong presence.

After failing to show up at the military academy where he was enlisted in Nigeria in 2006, Ogwuche instead went to study at the University of Glamorgan. There he adopted the nickname "The Lion of God" and threatened to cut off the hands of "kuffars," or apostates, according to his social media posts. "Those who strive in the path of Allah love death like the kuffar (non-believer) love life, hahaha. Let them know, we are always ready to meet our lord anytime he wills," he posted on Facebook in 2010.

Though university classmates expressed shock at his arrest, a pattern of such behaviour had led to the son of a respected retired lieutenant-colonel being, on the radar of Nigerian intelligence officials for "several years," a senior security source told the Guardian. He was briefly detained in 2011 after travelling from the UK.

"He was again arrested in December last year in Abuja. But human rights organisations and his father said his rights were being violated, so we released him on bail. He immediately jumped bail and hasn't entered Nigeria until he came back for [the Nyanya bomb] assignments," said Mike Omeri, the head of the government National Orientation Agency. "Most of Boko Haram's senior commanders have been to Sudan or studied there. We know that those who travel there are at high risk of being radicalised," Omeri added. Ogwuche's name was among seven others that came up again after intelligence officials arrested a local Boko Haram ringleader in Kano – Nigeria's second city – days after the Nyanya bombings.

"Five other [Nyanya suspects] are in custody in Nigeria and one is at large," Omeri said.

An official said Ogwuche had been "furious" after his initial arrest last year.