* Bomb blast hits bus park in second biggest city
* Jonathan says Boko Haram linked to other Jihadist groups (Adds new bombing, quotes, background, details)
By Mike Oboh
KANO, Nigeria, Jan 26 (Reuters) - Gunmen kidnapped a German citizen working on a construction site in Nigeria's second city of Kano on Thursday, the police commissioner said, the latest violence to hit the city plagued by Islamist insurgents for weeks.
"We got a report today that a German was kidnapped at his working site with (Nigerian construction firm) Dantata Sawoe at the flyover bridge along Kano's Zaria road this afternoon," Kano police commissioner Ibrahim Idris told Reuters.
"We are working on it. We are trying to see what we can do to track them down," he said.
Radical Islamist sect Boko Haram has increasingly moved into Kano, a city of around 10 milion people, from its homebase in the remote northeast. A coordinated series of gun and bomb attacks killed 186 people there on Friday.
Kidnapping of foreigners has become a common tactic of al Qaeda's north African wing, Al Qaeda in the Islamic Maghreb (AQIM), which operates out of Nigeria's neighbour Niger, as well as Mali, Algeria and Mauritania, and which officials believe has links with Nigerian militants.
In May, a Briton and an Italian were kidnapped in northern Nigeria, in Kano state, and were thought to have been taken over the border into Niger. A video was released in August which appeared to show them blindfolded and on their knees, saying they were being held by al Qaeda.
President Goodluck Jonathan told Reuters in an interview on Thursday that Boko Haram had made contact with other jihadist groups operating in the region, echoing views by security experts that AQIM has trained and supported some Boko Haram militants.
He challenged the group to identify themselves and state their demands as a basis for talks.
Militants planted a drinks' can full of explosives in a bus park in a neighbourhood of Kano populated by minority Christian southerners, causing a blast that wounded five people, witnesses said, the latest violence to hit the city after a coordinated strike last week killed 186 people.
"The explosive tin can was thrown in between two buses ... one of the bus was badly damaged, there were many people who are travelling to the south because of the Boko Haram problem," witness, Abel Bestway, 47, who works at one of the bus service operaters, said. "The park was jam packed. It was terrible."
Army spokesperson for Kano Lieutenant Colonel Iweha Ikedichie confirmed the attack on the park and told journalists other bombs had been discovered.
"Three other explosives were discovered in the park,the number of injured person is five, one of the who was unconcious was revived at a private clinic at a nearby street," Ikedichie said.
Jonathan sacked and replaced the chief of police and his six deputies on Wednesday, after a series of blunders including the escape from custody of the main suspect in a Christmas Day church bombing that killed 37 people.
Boko Haram, which in the Hausa language of northern Nigeria means "Western education is sinful", is loosely modelled on the Taliban movement in Afghanistan. It became active around 2003 and is concentrated mainly in the northern Nigerian states.
It killed more than 500 people last year and more than 250 in the first weeks of 2012 in gun and bomb attacks, Human Rights Watch says. (Additional reporting by Joe Brock in Abuja; Writing by Tim Cocks)