Katsina - Two blasts by female suicide bombers killed three people and injured 13 in Nigeria's Kano city on Monday, bringing the number of attacks this week in the area to five and overshadowing festivities marking the end of Ramadan.
The violence blamed on Boko Haram Islamists marred what was supposed to be a festive day in Kano, a city of more than six million people and the largest in Nigeria's mainly Muslim north.
Kano typically celebrates Eid al-Fitr, the end of Islam's holy fasting month, with a lavish parade on horseback led by the local emir.
But those plans were scrapped late Sunday following a bombing at a church that killed five people and an attempted suicide attack by a woman at a university that was stopped by police but left five wounded.
On Monday, a woman detonated low-calibre explosives packed to her torso at a petrol station in the Hotoro area on the outskirts of the city, targeting women who had lined up to buy kerosene, Kano police spokesman Musa Magaji Majia told AFP.
The queue was long, said area vendor Habibu Ali, because the widely used cooking gas is often in short supply and when a new shipment comes in women typically rush to their local vendor.
Majia said 10 victims were rushed to the hospital after the blast that went off at roughly 10:30 am (0930 GMT) and that three had died.
Hotoro area resident Shehu Mudi said he saw burning jerry cans and ambulances carting away victims minutes after the blast.- Shopping centre targeted -
Roughly three hours after the petrol station blast another female bomber approached the Trade Fair Complex in a key commercial district, Kano state police chief Aderele Shinaba told AFP.
She was stopped at the gate and blew herself up, he added.
"It was the same modus operandi," Shinaba said. "Six people were injured, including two (police) officers."
The target holds symbolic importance in Kano, lying just next to the brand new Ado Bayero Shopping Centre, which opened in March to huge public excitement.
The launch of a modern shopping complex, including the only northern Nigeria outlet of the South African retailer Shoprite, was seen as a sign that the restive city was still attractive to investors, despite the waves of Islamist violence.
While there was no immediate claim of responsibility, Boko Haram, the extremist group blamed for killing more than 10,000 people in Nigeria since 2009, was likely to be held responsible for the latest bloodshed.
Double bombings on Sunday and Monday as well as an attack at a bus station on Thursday that killed at least four people underscored Boko Haram's commitment to striking Kano after attacks in the city had declined earlier this year.
In a wave of assaults in key urban centres, including Kano and the capital Abuja, the militant group has in recent months shown that it plans to further expand its uprising outside its stronghold in the remote northeast.- Spreading across border -
Boko Haram, fighting to create an Islamic state in Nigeria's mostly Muslim north, is widely viewed by experts as having a largely domestic agenda.
But neighbouring Cameroon has seen a spike in unrest in recent months, raising concern that the insurgency may spread beyond Nigeria's borders, creating a wider crisis which the region's troubled militaries are ill-equiped to contain.
Two attacks in northern Cameroon on Sunday killed at least 15 people, with the wife of the country's deputy prime minister Amadou Ali among a dozen people reportedly kidnapped, according to security sources.
"Barbarism has crossed our borders," said Cameroon's minister of communications, Issa Tchiroma Bakary, after the incident.
The attacks have worried residents and expats living in Cameroon, which is unused to the level of violence Nigeria has faced at the hands of militants.
"The situation is catastrophic. It is getting worse," a French citizen living in the north of the country told AFP on condition of anonymity.
The dramatic raids in the Kolofata region -- a haven for Boko Haram activities -- follow the deaths of several Cameroonian soldiers and gendarmes in two attacks blamed on the militants on Thursday and Friday.
Nigeria says Boko Haram fighters typically escape capture by fleeing across Cameroon's porous borders.
Relations between Nigeria and Cameroon have long been troubled, including a bitter dispute over the Bakassi region in the south, but the neighbours have vowed to work together more closely to combat Boko Haram.