A German man shot and killed two Italians in a pub after an argument about past World Cup performances of their respective teams, police said.

"According to our current investigations, the three men got into an argument in the pub in the morning about, among other things, the success of Italy and Germany in previous World Cups," police in Hanover, northern Germany, said.

"After this, the suspect is thought to have left the pub, returned a bit later and fired at the two victims," the statement said.

One of the victims, a 47-year-old, died mid-morning on Monday of his injuries in hospital. The other, 49, died later.

Police are now urgently searching for the suspect, a 42-year-old German man from Hanover.

Authorities found a weapon, a 9mm pistol, in the vicinity of the pub.