The Electronic Assembly Systems unit, which employs 2,100 people, "no longer belongs to Siemens' core business" and operates in a "very competitive" market, the spokesman said, confirming in part a report in the daily Süddeutsche Zeitung.
The unit will be turned into a separate legal entity, he said, a move that is usually the precursor to a sale, merger or closure.
Siemens wants to sell the division, which posted yearly sales of several hundred million euros last year, by the end of the current fiscal year to September 30, the newspaper said.
Half of its employees work in Munich in southern Germany where Siemens has its headquarters.
Earlier this week, Siemens, which has been rocked by a scandal over how it obtained foreign contracts, announced it would take a charge of €900 million ($1.4 billion) due to problems with a range of major projects.
The group, whose operations span lightbulbs, computers, power turbines and trains, said it had been unable to keep up with the contracts it signed in the past few years.