By Ibrahim, Mshelizza and Mike Oboh
MAIDUGURI/KANO, Nigeria (Reuters) - An explosion targeting a security patrol outside a bank killed two soldiers and a policeman on Tuesday in the northeast Nigerian city of Maiduguri, the centre of an Islamist insurgency, witnesses and a hospital official said.
The blast followed a coordinated strike on a bus park in the northern city of Kano on Monday involving several bombs, including one suicide attack that killed at least 25 people, according to a Reuters witness.
After a lull this month, violence in parts of northern Nigeria plagued by Islamist insurgent group Boko Haram is on the rise again. There has been no claim of responsibility for recent attacks, but the Islamists are prime suspects.
"I was in the banking hall when I heard a loud explosion. I rushed out of the bank and I saw a military vehicle which had been hit, and some soldiers helping their injured colleagues," said Peter Soloman, a witness to the Maiduguri attack who saw three bodies pulled from the vehicle wreckage.
Baba Umar, a mortuary attendant, told Reuters he received the bodies of two dead soldiers and one policeman at the Maiduguri Teaching Hospital.
Boko Haram, which wants an Islamic state in religiously mixed Nigeria, has killed many hundreds in gun and bomb attacks since it intensified its insurgency two years ago, including 186 people killed in a strike on Kano in January 2012.
It and other Islamist groups are now seen as the main threat to Africa's top oil producer, since militancy in the southeast oil-producing Niger Delta region subsided under a 2009 amnesty.
Maiduguri is where Boko Haram first launched an uprising against the government in 2009 and has since been the sect's main stronghold since then.
Police said on Tuesday the explosions at the bus park in the Sabon Gari area of Kano on Monday had also wounded 65 people, many of them suffering burns.
Witnesses and police said that at least one of the blasts was the work of a suicide bomber, who drove a Volkswagen Golf car into a bus before detonating a bomb.
Suspected Boko Haram militants also attacked three schools on Monday in Maiduguri, killing three teachers and wounding three female students, police said.
On Monday, an audio tape emerged of a man saying he was the father of a family of seven French tourists kidnapped by Boko Haram militants. He read out a threat by them to increase kidnappings and suicide bombings in Cameroon, if authorities there detained more of the group's followers.
The French family was kidnapped from north Cameroon last month but is believed to be being held in Nigeria. Boko Haram has a presence in Nigeria, Cameroon, Niger and Chad, where the four countries meet on the threshold of the Sahara.
Western governments fear ties with groups like al Qaeda's north African wing have pushed Nigerian Islamists towards a more explicitly anti-Western agenda since France launched an operation to force jihadists out of northern Mali in January.
(Additional reporting by Chukwuemeka Madu in Kano; Writing by Tim Cocks; Editing by Jon Hemming and Pravin Char)